In all honesty, the only reason that the Canaan clip is funny is because it turns out that what the guy said was right, I'm pretty sure that's where they were going with that joke.
For the Monochromatic clip I'm pretty sure they were going for a "you jinxed it dumbass" moment(when you look at what the teacher says...) but took things a little too far.
There are times when japanese animation gets a little too carried away with boob jokes, but seriously, nobody makes boob humor better than Japan, at least not without resorting to crude in-jokes and stuff only adults would understand.
In all honesty, it's a flawed sense of 'fanservice' and much more the creator having a fantasy of their own and hoping the viewers will get a cheep thrill out of it. It's why I like animes like Asobi Ni Ikku Yo and Divergence Eve so much. They have just the right sense about when and where to use fanservice without resorting to such 'insulting' tactics.
My question though is why.....seriously...unless it's comic relief it doesn't need to be there.(especially random pantie shots, seriously...wtf...) I'll accept an overly buxom character....but other than that....*shrugs*