To give a sloppy blowjob to a non-erect penis. When a guy can't get it up, but the girl sucks on his loose rope anyways in a messy fashion.
"Darnelle couldn't get it up last night bc he was too drunk, but I slacked him up anyways"
"Wow, what a good person you are!"
"Wow, what a good person you are!"
by batistaxxx2 October 23, 2020
 Get the Slackedmug.
Get the Slackedmug. by B-rad dazzle March 3, 2019
 Get the trap on slackmug.
Get the trap on slackmug. by ItsVinnyBrahh April 8, 2019
 Get the Big Slackingmug.
Get the Big Slackingmug. by SCOOTS4LIFE September 14, 2016
 Get the Slack artistmug.
Get the Slack artistmug. by Ppmán June 10, 2020
 Get the Slackedmug.
Get the Slackedmug. by anonymous May 2, 2025
 Get the Jacking my slacksmug.
Get the Jacking my slacksmug. 