I always called bugs that disappear when you debug your program or appear at different places than expected a “Heisenbug”. Sometimes I add a nice subtitle like “it knows it’s being watched”

However I just found out that this is indeed the proper name for this kind of bugs according to the Jargon File:

A bug that disappears or alters its behavior when one attempts to probe or isolate it.

And this is exactly what I’m talking about when I say “Heisenbug”. Great