My (NB19) bf (18M) doesnt stop making sexual jokes to me after I told him to stop multiple times is this bad?

So, i know its all just jokes, but it makes me really uncomfortable when he does it, so I told him to stop, first he said he'll promise to stop, then he did it more and I called him out on it again and he just forgot that he promised the last time but he for real promises to not do it anymore bc he doesnt wanna make me uncomfortable, but then he does it more and, ok for the first time sure maybe he did genuinely forget I cant blame him on that, but after a second time, its just getting really annoying. He also does it in the worst moments, like id be upset and he does these weird jokes, or he says stuff like that he'll fuck me in my sleep, which i used to think was funny but its making me feel weird. Anyway is this really a bad thing that he keeps forgetting his promises