Short for "please", used in email by lazy asshats who put the minimum possible effort into being polite. Usually used in messges demanding something that's trivial for them but a PITA for you.

Internet persona(s) who happens to follow you and you happen to follow them back and maintain communication with and have a mutual liking for eachother whether it be friendship wise, etc. (Mutuals if more than one mutual)

Shorthand for please, but nowadays since texting shorthand isn't really used, it has actually become something of a separate entity. It has made it into verbal speech, such as "lol", and is pronounced "plz" or "pluz". In this context, in in and of itself can be used to mean:

"oh please" used to call out one's bullshit.
or
"please no" a subdued beg for mercy, usually from an online roasting.

pls = please

more specifically, it's used as an appeal.

Parking Lot Syndrome. When a group of friends stand around in the parking lot talking and chatting after dinner, a movie, or an event. This usually occurs when deciding on what to do next and can last a few minutes. However, it's only considered PLS if it lasts a considerable amount of time.

Post Lunch Sleepiness: The greatest and most dangerous disorder in America today. It affects millions of American workers and or students each and every weekday of the year. The symptoms include lethargy, a strong urge to sleep no matter where you are at the moment, and an inability to focus on anything no matter how interesting it may be.

pls or plys is used mostly by Turks at mmorpgs games, especialy at SRO. It's the word Please actually but in turk dialect