Green’s Dictionary of Slang

1. (US black) to protect oneself in those areas of one’s life where one might be vulnerable.

2003

Urban Dict. 8 July 🌐 d up. to put up your defenses, your guard. d up bitch your about to get snuffed.

2. to defecate [pun on sense 1 + initial letter of SE defecate].

1997–2001

Online Sl. Dict. 🌐 D-up v 1. to defecate. (‘Man I need to D-up.’).