To have sexual intercourse with. Synonym for "fuck".
Comes from the spelling of 428 on a blackberry world edition or bold. 428 without holding shift is (s.e.x). Discovered while drunk texting directions. "428 on wellington"
1."Did you 428 (four twenty-eight) Steph last night?"
2."Hey Bitch, wanna 428 (four two-eight)?" (a pun on the word fornicate)