"Flingin'" is a word used to describe someone who is "funny looking", in a more subtle manner. The origin of the word can be traced to Shanghai, and first came into use in the late2000's.
The act of leaving your boyfriend or husband while at a public venue such as a club or bar to go fuck a stranger you met and then return to your husband or boyfriend at that same venue a short time later.
Don't worry about my husband, he'll wait here patiently for me while I go flinging.