Usually, if something that should've been obvious gets me by surprise. Like, you know how a character is, you know about their habits, and then, during a completely mundane situation, where you completely forgot about certain peculiarities, the absurdity strikes hard, as the character behaves exactly like they would, and you just go in your head "Yeah, that's just like them.". If you can pull off this kind of logical surprise that's going to get me.
I want to separate this really hard from embarrassing oneself, though. If the character just acts awkward and their behavior is just thought to make them clowning around, I merely cringe in a bad way. That's merely sad to watch, and I usually hve to break up and get my mind somewhere else ifthat overwhelms me.