This is a trick that I've thought of, but haven't actually done to anyone yet, because it seems...really mean.
I have this james dean lighter that someone gave me. It's a lighter with a clicker, where you can adjust the flame....anyways. When I got it, it was like a crack head lighter, even on the lowest setting, the flame was HUGE.
So my brother fucked with it to lower it for me. Now, when you have it on low, it's a nice normal sized flame. But if you move it up more than just a little it'll go back to crack head lighter status.
So what I've thought of doing is blazing a bowl with a few people, let my lighter be the one to get passed around. Let it go around once with the flame normal, and then when it gets back to me, before I pass it, nudge it up. The next person who hits it really won't be expecting it, because they already used the lighter once.
But yeah, I'm not really into mean pranks, so I haven't done it to anyone....yet.