Chest hair on men, which is allowed to grow without shaving at the top of the chest (in any of various shapes), and shaved clean from well above the nipples down to the waistline.
A chestache allows a manly appearance in a partially unbuttoned shirt, but with a cleaner appearance below the chest whilst shirtless.
"I like his chestache, but it sure gives him a weird tan line."
"I love running my fingers through his chestache."
"His handlebar chestache is oddly appealing, but I wonder how much wax it takes to do that"
A mustache that is only partially grown. It is usually found among guys in high school whom are too unkept to bother shaving before most of their facial hair comes in. Their mustaches look really crappy.