OK, here goes: If you want to see Otacon scold Snake, just do the following:

1) Watch the TV in the crew's lounge, then contact Otacon again. He'll scold Snake for being a couch potato instead of doing his duties.

2) Light up a cigarette and contact Otacon. He will give Snake a unwanted speech about the dangers of smoking, blowing his cover when doing so, and informing him that he has to think for other people's health as do his.

3) Hide yourself in a locker and contact Otacon. When Snake makes a crack about that "wee" accident, watch what happens!

4) For you guys who love adult humor, look at the posters in First Person View Mode, and contact Otacon. You'll see Snake doing the unthinkable.