Any «Yeah, fuck you too, asshole» tips, please ? :)

Hi everyone

Just today, I’ve helped a female friend, her wordpress blog had been hacked by a pirate. She was partly guilty in this, she had kept online old pirated wordpress themes, and one of them contained a security flaw that allowed the pirate to enter, take control, and upload an unwanted file, that file being like a “control tower” for future activities.
As such, frankly, this is no big deal, I’ve seen much worse in my (looking back : horrible) past dealing with various security flaws, I’ve learned security the harsh way ^^
Cleaning the shit was quite easy, in itself, this is no big deal, I’m – sadly T_T – fully aware of the ways to clean, find and remove entry points, and make sure no shit was left, at least in cases like that one.

I’m posting here to ask another question, I searched, but my google-fu is legendary for sucking ^^;;

Would you know if there are javascripts or nasty codes that I could fetch and place instead, inside the “control tower” file, so that it bothers the person who intended to use it ? No viruses, I don’t want to play a dirty game, against a pro I would certainly be toast, I want it to stay soft teasing.

When the bad person would check that page, instead of his control tower, he’d have his computer annoy him.
It could become all slow because of a heavy javascript made to max CPU usage, perhaps (but sadly, his browser would probably offer him to stop the script, if only he has javascripts activated and allowed).
Or it could stay locked while playing him an irritating music.
Or it could go fullscreen and flashing super fast ugly pictures (ever heard of Staggering Beauty ? No need to thank me, mwahahahaaaaa ! – NOT for epileptic people).
Well, something like that ^^
Would you know if there are codes that could be easily pasted to generate some of these effects ? If there are, I’d be glad to paste it

Thanks if you’ve got inspiration source, and remember, no virus or real bad shit, it’s all about teasing and annoying