Bruce, depsite his hate for Joker, never actually really hurt Joker. He would snap in anger sometimes and put Arthur to Arkham, but he very rarely actually hurt Joker.

Joker knew that well and he just loved teasing Bruce...

Bruce was on his patrol, making sure the city is safe, when he suddenly feels a tight hug from behind, along with a chuckle. Of course, it was Joker...Bruce sighs and says calmly

"What do you want, Joker? I'm not in the mood."