get an erection; acquire an erect penis
Horny slut to drunken bum: FIRM UP, DARLING
222👍 45👎
to acquire a more toned physique
I can't believe she just ate that entire cake! She'll never firm up before her wedding
To take something that is hard to manage and complete the task
Benjamin - "This maths work is so hard fam"
Tyrese - "Firm it up"