Iron Man 2: Did you just do that? (SPOILER ALERT!)

I think I have given enough time for all the hardcore nerds to see Iron Man 2 so here goes. Whilst diving into Tony Stark's problem with alcohol abuse a scene takes place in the movie during Tony's birthday where he is on stage in the Iron Man uniform and tells the crowd, "A lot of people ask me how i go to the bathroom in this thing(pause)...like that." Now this lame joke in itself could be a Marvel Mishap, but it's not. Tony Stark always has his machines bolt on the iron man suit while he is fully clothed so do the robots somehow pull off his underwear and replace them with a diaper every time he suits up or did he just piss himself? I'm going to go with the second choice. Not very heroic...and pretty lame.