the process of surprising somebody by means of moustache. the victim of a Mo-sprise is generally unhappy in receiving the sudden shock that can result in the unexpected change in an aquantances facial hair-do.
a classic example of Mo-sprise is when one grows a beard to disguise the attempts of growing a moustache. when the moustache is in full bloom the cultivator shaves his/her beard leaving only the top lip unshaven.
a victim is then selected and upon greeting they are "Mo-sprised" when they notice the moustache that has grown, somewhat exponentially on the face of the offender.