The act of snitching on someone in order to get out of trouble. Just like the rapper Tekashi 6ix9ine.
SpongeBob: There is a rat in the deep blue sea. He's 6ix9ining just so he could be free. Now he's got me in here facing penalties.
The act of snitching, or being bold on the internet while knowing you are completely safe from harm.
-Yo Terry just 6ix9in'ed to the principal about you having weed.
-"That nigga a bitch and won't see me blood". "you 6ix9ineing I tried to see you yesterday at the park but you ran to your car and drove off pussy nigga"