If you don't know, a pick me girl is a girl who would have this sort of attitude: "I'm not like the other girls" "I like real boy shit like beer and action movies " "I don't like being around girls because they are so catty"
Basically always seeking male validation.
A pick me boy is a boy who would have this sort of attitude: *to a girl they like* "You're so cute! You probably would never like me though because I'm so ugly" *uses googly eye emojis*
Basically they use self-deprecation as a form of manipulating and guilt-tripping their crush into liking them.