To do that which fulfills one's own desires, expectations, or ambitions, especially when failing to consider those of anyone else. It really doesn't matter to me how you arrange the furniture in here, so just please yourself! Look, Tom and his wife are always going to please themselves, so don't tie up everything you want to do on this trip with them.
set phrase I accept your decision or preference; suit yourself. The phrase typically implies that the speaker disagrees with (and is perhaps irritated by) the decision. A: "I would just rather not go to a wedding where I won't know anyone." B: "Fine, please yourself. I'll just go by myself."
to do what one wishes. We don't mind whether you stay or not. Please yourself! The boss preferred me to work late, but he told me to please myself.