What's the right possessive pronoun for "nobody"? [duplicate]

Possible Duplicate:
Is there a correct gender-neutral, singular pronoun (“his” versus “her” versus “their”)?
None as plural indefinite pronoun

Should it be his or their here:

A: Why did you put on that baseball cap?

B: Because I want to take shower

A: Nobody takes shower with his cap on.


You could leave it as is, but a gender-generic way would be:

Nobody takes a shower with their cap on.

-or-

Nobody showers with their cap on.