I haven't had the chance, but a friend of mine yes, and I had the honor to see it. It happened today, I was next to my teacher who is really hot, a petite with dark hair, brown eyes, around 24 (yes she is young) really cool to hang out with, well she was wearing a sleeveless shirt, blue jeans, and shoes. So she was reaching for something that was really high and my friend was in the back of her and start tickling her armpit, she put her arms down and said "don't do that", and he said "why not?", "because i'm going to hit you", and we laugh, and that's it. Sorry I sucked writing.