Grim-rim 

A grim-rim is where the girl's anus is covered with cum and has to take laxatives in order for her to shit crazily. She then smears the brown goodness and the guy (or girl if she like to scissor other girls or girls that are "friends" and make out for "fun", when deep down, they are in fact lesbians) has to put his mouth in the anus and tongue deep inside of the chocolate butt brownie dispenser (anus) and lick in a clockwise motion whilst she has to shit like mad.

After when her asshole has been clean, he has to vomit back inside her anus and then lick again until he realised that he has fallen into that part of life where "what the fuck" is an understating term for how much of a disgusting bastard he really is. This, is not as bad as munging, which is the most un-holiest thing you will ever hear and can help in the throwing up stage in this definition, if you love to smell like a baby's ass when wearing a used nappy for a week.

Guy: 'Ever heard of the "grim-rim?" '
Girl: 'No, but what is it?'
Guy: 'Please... allow me to show you. After, you will realise that this might become your fantasy as well as mine.'

Grim-rim by Cosworth YBD September 12, 2019

G-Rim 

A rim job in which the receiver is wearing a G-String, and the giver's tongue keeps twanging it from side-to-side.

Some shit flicked into my eye while I was giving Shelly a G-Rim.

G-Rim by TheUrbanScholar69 June 27, 2021

G-Rim 

An usually large fold of skin found on the back of obese necks. Specifically located below the bottom of a baseball hat and above their shirt collar. The size of these fuckers disproportionally enlarge with weight gain while being immune to weight loss. Tend to collects beads of sweat.

I can't stop staring at that dudes G-Rim, it really must be a bitch to shave.

G-Rim by Faregounder July 24, 2018