30 Share definition Flag Chicago slang, A 30 is a Glock with an extended clip that holds 30 rounds in it. I keep the 30 with me where ever I go you know I do it 30 by SouthSide Murderapolis !! March 13, 2014 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