What do bạn do in this situation?

So they're annoying, they've bee an asshole to me, and I don't care about them?

I'd cú đấm that muggle in the fucking face! Besides, NO ONE gets away with being an asshole to me... except my sister... because my sister is scary....

I'd tell them to shut the fuck up and to talk about something worthwhile.

I would say strange things completely unrelated to the subject of their boyfriend/girlfriend and creep them out until they leave. o3o

Oh like this:
Me:SHUT THE FUCK UP, OK!
then talk about how fucked up my sister is to me.

This has actually happened before this is how it went.

Frien:And then Trent kissed me! He actually kissed me like on the lips!
Me: *pokes rau xà lách, salad bored* So Trent as in the kid from homeroom who runs like a girl, hoặc Trent as in the one who was dating me last week? (lies I never went out with him)
Friend: bạn were dating Trent?!
Me: Yup, he đã đưa ý kiến that he really wanted to be with a dumb blonde. (me and my friend make fun of eachother)
Friend: How could he! *starts crying*
Me: Are bạn kidding me? I never dated him he's my cousin!
Friend: oh... Why would bạn say that?!
Me: Because bạn broke up with Brian two days ago, to be with Trent, kissed Trent on the first date, and now your already jealous.

I'd tell them to shut the fuck up and if she asked me why I'd bluntly tell her "because I do not care about your tình yêu life m'kay"

What my friend tells me about my anime obsession:

"You need a life outside of this."

Umm... I would say just ask them "Hey, uh, can we talk about something else?" hoặc just gently make aware of them that he/she is all they talk about.

...ಠ_ಠ