Let's cut the poor guy some slack. My interpretation is that she wants his penis to be smaller.
Or, if this how she talks about him, then it's also possible that she wants him to use his penis on her, which I don't blame the guy one bit for not wanting to do.
I'll even go one better. He should stick his penis in her mouth so can't say stuff like that, and keep it there!
I wonder what his answer would have been towards her. Changing her brain is one thought that comes to mind.
This recalls the urban myth of Madam de Gaulle. The answer she allegedly gave to an innocent question is one for the ages. http://www.snopes.com/quotes/degaulle.asp