Used in SMS language (texting language) to express an individual's true reaction to a humorous text message. This abbreviation is a more accurate alternative to writing "lol". Clearly, he/she is not laughing out loud in a literal sense, but is instead staring at his/her mobile phone while brandishing a gay little smirk.
AJ: Dude, she is seriouslysmokin' hot. I would be her on-demand asshole licker. Let me explain to you what that entails. I would lick her asshole on-demand.
Karthik: gls
Gurren Lagann Syndrome - When an anime has multiple openings, but they are the same song with different lyrics and visuals. Examples of this include both openings of Gurren Lagann and the openings for Hunter x Hunter 2011.
"This anime has good openings, but suffers from GLS"