How about I not tip the delivery guy when he comes?
Did he do something wrong to your order?
He's attractive, that's why I'm not tipping him.
I'm uncertain what attraction has to do with a tip. I think choosing to not tip is fine, personally.
Nah, just cause, and I got better things to do.
That doesn't seem quite fair. It's reasonable to decide to tip someone but you should have a good reason for it. I wouldn't do that just for no reason.