Shawty is actually in prevent
Cause the one in front is working deep threat, yep
Wale uses a football reference here as he has been know to do in many of his songs (here for example). Shawty is in “prevent” (i.e. shunning advancements) or in defense mode because the guy courting her currently is aiming for a long term relationship (deep threat).
To help improve the meaning of these lyrics, visit "Bad" by Wale (Ft. Tiara Thomas) Lyrics 4 and leave a comment on the lyrics box