The full form of TWOT is total waste of time.
The acronym “TWOT” is most commonly understood to mean the phrase “total waste of time.” It is most often used as a comment on videos or photos by internet users who think their time could have been better spent doing something else rather than invest the time spent in watching or looking at the picture or video.

Origin of TWOT
The phrase “that was a waste of time” has been used for years in regular offline communication when someone felt they invested time that could have been better spent elsewhere. With the dawn of the internet, some of the popular phrases that already existed were reduced to acronyms like “twot” used to represent common phrases already spoken. These phrases were reduced to acronyms to make electronic communication easier, faster, and more convenient for users, while still allowing them to maintain a regular conversation. The exact year that the phrase first appeared and the acronym first appeared is unknown.

Other Meanings
According to user contributions of the Urban Dictionary, the acronym “twot” can also be used as a stand-alone word for an alternate spelling of the insult “twat.” “Twat” is used to refer to a female’s vagina or can be used to describe a person who is useless and/or successfully getting on someone else’s nerves with their behavior.

Example Conversations
A text conversation between two friends.

Friend 1: Hey, you need to watch this video (sends random link with the message)
Friend 2: (replies after watching link) What was that?
Friend 1: What? I thought it was funny!
Friend 2: No, what that was, is a twot!