Prime candidates of the "Mousey" classification have innocent facial characteristics. Usually rounded cheeks and chin. Classifiable as "cute as a mouse" yet not restricting the definition to just "cute." "Cute" and "Mousey" are two different things, that sometimes go hand in hand, but have been known to also not.
Mousey can range in attractiveness levels, from substandard to above average, but are all genuinely unique in their own individual regards, and may vary according to tastes of the beholder.
OG 2: That Mousey girl?
OG 1: Cheaa guyyyy.
OG 2: "BABE!"
Dude2: You idiot you bolted the motherboard directly to the case!