Heisenbug
A heisenbug (named after the Heisenberg Uncertainty Principle) is a computer bug that disappears or alters its characteristics when an attempt is made to study it.

Bohrbug
A Bohr bug or bohrbug (named after the Bohr atom model) is a bug that makes itself manifest consistently under a well-defined (but possibly unknown) set of conditions.

Mandelbug
A mandelbug (named after fractal innovator Benoît Mandelbrot) is a computer bug whose causes are so complex that its behavior appears chaotic.

Schroedinbug
A schroedinbug is a bug that manifests only after someone reading source code or using the program in an unusual way notices that it never should have worked in the first place, at which point the program promptly stops working for everybody until fixed.

Phase of the Moon bug
The “phase of the moon” is sometimes spouted as a silly parameter on which a bug might depend, such as when exasperated after trying to isolate the true cause. The Jargon File documents two rare instances in which data processing problems were actually caused by phase-of-the-moon timing.

Statistical bug
Statistical bugs can only be detected in aggregates and not in single runs of a section of code.

Source : Wikipedia – Unusual software bug