my older sister cut her fiances hair once with a clipper and unfortunatly the head was loose and came off!
she gouged a 3 inch line that went straight to the scalp! it say he was furious would be a major understatement

afetr chasing her around the garden for 10 mins he finally calmed down and let my mum try to repair the damage
he had to go to work with a baseball cap for at least a couple of weeks, his coworkers never let him forget it
so the moral is that self grooming can be cheaper but if done wrong can have serious consequences for your love life!