Do it jokes

Standard gags

Mathematicians do it by the numbers.
Mathematicians do it constantly.
Mathematicians do it continuously.
Mathematicians do it discretely.
Mathematicians do it forever if they can do one and can do one more.
Mathematicians do it in numbers.
Mathematicians do it in theory.
Mathematicians do it to prove themselves.
Mathematicians do it with a Minkowski sausage.
Mathematicians do it with relations.
Mathematicians do it with Nobel's wife.
Mathematicians do it without limit.
Mathematicians do it ad infinitum.
Mathematicians have to prove they did it.
Mathematicians do not do it. They leave it as an exercise to the reader.

If we get into specialized areas, we find that...

Aerodynamicists do it in drag.

Algebraic geometers do it for variety.
Algebraic geometers do it three-fold.

Algebraists do it by symbolic manipulation.
Algebraists do it in a ring.
Algebraists do it in fields.
Algebraists do it in groups.
Algebraists do it with rings.

Analysts do it continuously.
Analysts do it smoothly.
Analysts do it almost everywhere.
Analysts do it to the limit.
Analysts do it with their real parts.

Analytic number theorists do it in the critical strip.
Analytic number theorists do it on the critical line.

Applied mathematicians do it by computer simulation.
Applied mathematicians do it with a real model.

AI researchers have tried to do it since the 60's but haven't yet succeeded.
AI researchers do it heuristically when principled techniques fail.

Astrophysicists do it in the dark.
Astrophysicists do it with telescopes.
Astrophysicists do it with large objects.

Banach spacers do it completely.

Bayesians do it with improper priors.

Catastrophe theorists do it falling off part of a sheet.

Chaoticians do it with sensitive dependence.

Class field theorists do it by capitulation.

Classical geometers do it with a straight edge.
Classical geometers do it from the right angle.
Classical geometers do it on the nine-point circle.

Combinatorists do it discretely.
Combinatorists do it as many ways as they can.

Commutative algebraists do it regularly.

Complex analysts do it between the sheets.
Complex analysts do it under a universal cover.
Complex analysts do it with imaginary parts.

Computer scientists do it depth-first.

Constructivists do it without excluding the middle.

Cosmologists do it in the first three minutes.

Decision theorists do it optimally.

Differential analysts do it in a degenerate case.

Differential geometers do it on smooth contours.
Differential geometers do it over and under the curves.

Functional analysts do it with compact support.
Functional analysts do it with degenerate colonels.

Galois theorists do it in a field.

Game theorists do it by dominance.
Game theorists do it with saddle points.
Game theorists score most often.

General relativists do it with curvature.
General relativists do it with rubber sheets and canteloupes.

Geometers do it with involutions.
Geometers do it symmetrically.

Graph theorists do it in four colors.
Graph theorists do it discretely.

Group theorists do it simply.
Group theorists do it with the Monster.

Hilbert spacers do it orthogonally.

Inductionists do it forever if they can do one and can do one more.

Large cardinals do it inaccessibly.

Linear programmers do it with nearest neighbors.

Logicians do it by choice.
Logicians do it consistently and completely.
Logicians do it incompletely or inconsistently.
Logicians do it necessarily and sufficiently.
Logicians do it with Jensen's device.
(Logicians do it) or [not (logicians do it)].

Mathematical physicists understand the theory of how to do it, but have difficulty obtaining practical results.

Matrix analysts don't do it until it is positive definite.
Matrix analysts do it within a Gershgorin disc.

Matrix computationalists do it by pivoting.
Matrix computationalists do it on a mesh.

Number theorists do it perfectly.
Number theorists do it rationally.
Number theorists do it prime number of times.

Physicists do it on the event horizon.
Physicists do it in waves.
Physicists do it with ropes and pulleys.
Physicists do it with vectors.
Physicists do it at the right moments.
Physicists do it with force.
Physicists do it on the spur of the moment.

Pure mathematicians do it rigorously.

Probabilists do it on random walks.
Probabilists do it stochastically.

Quantum physicists can either know how fast they do it, or where they do it, but not both.

Real analysts do it almost everywhere.
Real analysts do it uniformly.

Representation theorists do it for Schur.

Ring theorists do it ideally.

Set theorists do it with cardinals.
Set theorists do it with morass.

Statisticians do it continuously but discretely.
Statisticians do it when it counts.
Statisticians do it with 95% confidence.
Statisticians do it with large numbers.
Statisticians do it with only a 5% chance of being rejected.
Statisticians do it with two-tail T tests.
Statisticians do it. After all, it's only normal.
Statisticians probably do it.
Statisticians do all the standard deviations.
Statisticians would like to do it with the population, but only get a small sample.

Topologists do it on rubber sheets.
Topologists do it openly.
Togologists do it in multiply connected domains.
Topologists don't do it. They would rather knot.

Topos theorists do it pointlessly.

Variationists do it locally and globally.

Of course, famous folks did it too

Cantor did it diagonally.
Cantor did it 'till he was crazy.
Fermat tried to do it in the margin, but couldn't fit it in.
Galois did it the night before.
Heisenberg might have done it here.
Moebius always did it on the same side.
Markov does it with chains.
Newton did it standing on the shoulders of giants.
Turing did it but couldn't decide if he'd finished.