I went to rehab with a guy who said this happened to him, though he wasn't trying to make it happen on purpose.
He was a gay guy and I guess we were sharing stories among the other queers. This guy said that he was having a multi-day meth fueled fuck session with this person. He was getting fucked when he felt like a warm liquid was being poured in him. He initially thought that they guy was cumming but quickly realized that it was far too much liquid to be ejaculate. Just about as soon as he realized that, he said that he got very, very, very high,
He didn't appear to be lying and had no reason to lie. I mean if you've used enough meth to have a buildup of active metabolites, then there's no reason to believe that it doesn't work.,
Meth is cheap enough that I hope that most people wouldn't HAVE to resort to this to get their fix. Although if you have a piss fetish while high on meth then I say go for it, slugger.
The danger, of course, is that there's no way to measure the meth-to-piss ratio, so you have no idea how much you're gonna be getting. Whereas with actual crystal you can measure how much you want and just stick THAT up your ass (after diluting in water unless you want another hole burned into your bum)