When a boy says he wants to tap dat what does that mean?

Oh, dude, when a boy says he wants to "tap dat," he's not talking about fixing a leaky faucet. He's basically saying he wants to hook up or get intimate with someone. It's like his not-so-subtle way of saying he's interested in getting physical. So, like, be prepared for some smooth moves or awkward fumbling, depending on the guy.