[maximilian]

I read that, when he gave technical talks away from Caltech, he would have to use a pseudonym, so that the room wasn't packed full of people wanting to see "Famous Nobel Prize winning Feynman" give a talk. This way only the appropriate people in the physics dept would come to see his latest results.

[mhartl]

Both this anecdote and the parent comment can be found in "Surely You're Joking, Mr. Feynman". (N.B. The quote marks are correct: the title itself is a quote.)