Three. One to get the punchline, and one to point out the math is wrong.
My newt.
Just look at it. It's headed in One Direction and pointed in the other.
Hot wheels (First joke, hope you like it.)
About a day.
They can never get further than the tip!
Fedora Linux!
In the punchlines.
A short one with no punchline
With a cow-culator! (Rimshot)
Subtract her clothes, divide her legs, give her a square root and watch her multiply.