Had a new co-worker I was responsible for training. I am several years his junior, but he is working with a new language/framework I'm fluent in. Day 4 into training, he walks into my cubicle, sidles up next to me, I look up at him, he farts loudly, then (without seeming to realize what he's done) he proceeds to launch into a long-winded question about coding best practices.

If this were an isolated incident, I'd have written it off, but the dude did it again when he came to my desk and asked me to open a jar of pickles for him, and many times over during casual conversation.