sex up Share definition Flag to have physical contact with someone, such as making out, feeling up, or fucking. "That boy is so pure sex, I can't wait to sex him up." sex up by Sami August 25, 2003 Words you can keep railfan mug chonk mug chud mug based mug 67 mug slime mug mogging mug chopped mug thot mug glazing mug huzz mug yams mug larp mug unc mug cracked mug simp mug baddie mug bop mug lolcow mug