a Northern England expression intended to rudely dismiss someone or rudely tell them to leave, go away, akin to * scram, get lost! "
So, after I boinked her, we were done but she wouldn't just leave, so I says to the tart " okay, now, well, slag-off!" and then she left in a huff.
by Billiemski LeWiglud June 21, 2020
Get the slag-offmug. more or less being insulting or dorogatory in a sexual way..
"she is a slut"
"Oh Bob you fucked her last night stop slagging off"
"she is a slut"
"Oh Bob you fucked her last night stop slagging off"
by Nikki Gloom March 1, 2014
Get the slagging offmug. 
Get the Slag offmug.