Adjective. Refers to a person or action that is "lacking in balls," or lacking in courage or bravery.
Jimbob: So here's my number. You should call me sometime.
Leila: I don't call guys. You should call me!
Gertrude: OMG. That was so lackaballsical of him.
Gertrude: Why doesn't he just ask me out already? We've been "hanging out" all summer!
Leila: He's just lackaballsical like that.