Irritated skin on your upper lip, making it look like a mustache, which is especially unfortunate for females
After using Nair on her upper lip to remove her girl mustache DESPITE the instructions not to use it on the face, Kaitlin was rewarded with a handsomely dark rashtache
Gashface refers to someone with a facial configuration that quite closely resembles a female genitalia. Although it is quite unlikely that someone would in fact have a vagina located on their face, it is used as an insult and generally implies that someone is fugly.
Look at Ramsey Jouzy walkpast, what a ridiculously gashy gashface that boy has.