An imaginary time during the month when the cycles of the moon cause a man to be bitchy and irritable. Directly related to a woman's pre-menstrual cycle, a woman can ask a grumpy man whether or not he's on his 'mancycle'.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.

Half man, half bicycle.
(not to be confused with the half man, half popcicle, see mancicle)