Picking up on the "three at once" theme, the 1-bit computer I built in the 1980's has an instruction that does three things.
The computer only has one instruction, so I didn't bother to give the instruction a name. But it performs an input, an output and a 2-way branch. I hope this is weird enough to deserve mention in this thread. :)
The project was mentioned at least twice previously on HN: