Also, watch the damn movie (you know, if you like the genre... which almost certainly would mean that you have watched it... erm... never mind)
"Boards don't hit back..."
Lee is not a fan of O'Hara. This much is made obvious fairly early on in Enter the Dragon. O'Hara isn't really a fan of anyone. He fights dirty, and was involved in Lee's sister's death years ago. So, you know two things: they will fight in the tournament that makes up most of the movie, and that their fight will be a hard-fought throwdown.
Sure enough, Lee and O'Hara get the draw to fight each other. Lee, being the honorable sort, bows to his opponent, who - instead of bowing back - attempts to show his acumen by punching a board in half. Lee's reply is classic: "boards don't hit back".
He then proceeds to absolutely destroy O'Hara, who is unable to lay so much as a finger on him. The villain gets increasingly desperate, finally threatening Lee with a couple of broken bottles. Then Lee straight up Super Mario's the guy. It's all glorious.
Here is the scene.