My D&D group is currently playing a campaign. It went smoothly for the first half. And then, by request, I allowed two of the current players' friends to join the campaign, all of whom have no prior experience in roleplaying game aside from what this player told them about D&D.

The few next sessions, one of them started to make me and few fellow players uncomfortable by describing explicit sexual actions. His reasoning was "because my character is chaotic evil" - even though I told him privately that one of the rules in our session zero agreement was that there would be no explicit sexual activity in this campaign.

I even took the initiative to redo the session zero so he can participate in it and so I could hear his reasoning and expectations. From my side, I explained the usual about the tone of the adventures, what I expected from players, and my restriction on "you can flirt with female NPCs to get information, and female PC can go for a little skinship if you want, but no explicit ones. Also no descriptive gore".

And from his side, he said he understood what I wanted, and as long as he can do what he expects his character to do (we did another private talk about how would he handle the story, what the "endgame" of his character is, and how does his character would die if necessary), he said that he would do his best to react accordingly. He said he doesn't mind the agreement, and wants the story to run smoothly and wants his character to have a great time.

But the very next day, he did the same thing I told him not to "because his character has nothing to do in the night before we do a long rest".

**Is there any way to get around it, or should I give a possible "punishment" that have a lasting effect on his character? Or is it my fault as a DM for not being stern enough with the session zero rules?**

I want to make kicking him out a last resort.