Can someone explain what the big deal is about the phrase "that's what she said"?

Question

Can someone explain what the big deal is about the phrase "that's what she said"?

Answer 1

Its supposed to be funny in an implied sexual way, consider this-

Student A:  What did you think about that test?

Student B:  It was really hard!

Student A:  Thats what she said!

It all depends on your taste in humor.

Answer 2

Perverted humor... probably came from College kids, haha.

Answer 3

s*x jokes. They is funny.

Answer 4

I think saying that implies that you were with whoever the person is talking about recently.. it's usually ment sexually.