Nexting is a technique used to remove someone from your life in a clean, efficient manner that causes minimal to no drama. Tantrum whores, liars, users, schemers, drama queens, faggots and losers are typically the kinds of people who are subjected to nexting.
Dave: Can you believe it, Katie slept at Mikes house last night.
Jason: WTF, she told me she was at Mels all night and doesn't know anyone called Mike.
Dave: Man I am sick of all her lies, it's nexting time.
Jason: Fuck yeh, nexted.
Nexting is when you're walking / talking / hanging out with someone and they see another friend of theirs and immediately ditch you and start talking to them and leave you behind.
Kate: I saw you walking with Laurie a few minutes ago. Where is she?
Me: Laurie? Right. She nexted me for Kim.
Kate: Dang, sorry. I know what it's like to be nexted, nexting sucks.
The act of a parent sending one or more text messages to their kid as a "reminder" or "suggestion" of something the kid needs to do (possibly being construed by the kid as "nagging").