Getting your next relationship set up before dumping your current S/O. Generally involves cheating (at least emotionally) on your current partner with the intended future partner. Refers to playing on the monkeybars, where you don't let go of the first bar until you've grabbed on the second.
Bill: "Well, your brother just sent the Save The Dates for his third marriage - they haven't even finalized the divorce yet!"
Joe: "Yeah, the monkey branching SOB did the same for his second marriage as well - all his relationships 'overlap,' if ya know what I mean."
OR
Joe: "Sue and I decided to try an open relationship."
Bill: "I dunno, sounds like she's monkey branching to her *next* relationship."
when a girl already has a boyfriend but she gives her number to guys that she meets and flirts as if she were single. she's basically branching off from her boyfriend and establishing backups.
yo dude I saw your girl at starbucks giving her number to some guy. I don't think she saw me. it looks like she's monkey branching, you should dump her.
"dude, i had no time to eat before work today, and you know the bastards at work wont let me eat on the job. when i came home i ate brunchinnner to compensate for all those lost calories."
your typical brunchinner dish would constist of ground chuck beef, lettuce, and oatmeal, all mixed in one bowl and topped with ketchup, bananas, and balsamic vinegar. mmm.