When something (a situation, something that you see, hear, understand, realise, etc) figuratively 'screams' an idea to you, that means it very strongly and forcibly suggests that idea to you (a literal scream is hard to ignore).
The alarm bells, smoke and flames screamed 'Get out of the building,
NOW'.
The writer is suggesting that when a girl looks at you, sees you are looking at her butt, and she gives you a 'frick me' look, that action of hers suggests to you very strongly that she has a crush on you.
Scream (verb) (transitive or intransitive)
to state something in a loud way that is difficult to ignore, or to be
immediately obvious
‘Devil Dogs’, the headlines screamed.
It was the kind of shirt that screamed vulgarity.
It’s a badly written essay, and the grammatical mistakes just scream
out at you.
Scream (Macmillan Dictionary)