Anything bearing a Santa-like quality of holiday holly jolly cheer and merriment.
"Hey man, how do I look in my new Santa hat?"
"You look totally santastic!"

"Hey, what do you think of my new elf print boxer shorts?"
"Golly gee, them's are santastic! Let me try 'em on!"

"I just turned 14 and my boyfriend got me pregnant three months ago! I'm totally freaking out, my boyfriend dumped me and moved to China, and my parents kicked me out and I'm living in the alley behind McDonald's!!! What am I going to do, the due date is on Christmas Eve and I don't want to keep it but I'm afraid to get an abortion!!"
"Whoa your baby's birthday will be on Christmas Eve! That's totally santastic!"
by Shibben McFlibben III November 27, 2010
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Adjective to describe that comfortable satisfaction one gets from stuffing their head-holes with fat-and-sugar laden holiday food for a month. Also describes one's new larger physical profile from same.
Guy 1: Man, I've been chowing on pie and Christmas cookies non-stop for the last three weeks. I feel Santastic!

Guy 2: Yeah, you look Santastic, too, Tubbo!

Guy 1: Suck it.
by The Evil Steve December 18, 2008
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Santastic is a guy from Liege's Llama Habitat server, he is also known for being the best stalker in this world, if you join a game, he has alr joined and he must the waiting for you, he is also known as Santa, and he will give you presents if you ask him, he is a papulince, so, dont be closer to him, or you will become a papulince!
Oofrun: what are you doing?
Vincent: Trying to avoid Santastic's stalks
by Minced Meat July 11, 2020
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