Someone who cannot make any friends no matter how hard they try, works a dead-end job making less than $20k a year, lives with his parents past the age of 25, is fugly, fat, unattractive, emotionally immature, and mostly likely somewhere on the spectrum.
At the ten-year high school reunion, George (who was always a loner with no friends back in the day), was the only classmate to show-up stag. At 29, he still worked at a dead-end job making peanuts, still lived with his parents, 200 pounds overweight, face looking ugly as ever, had zero friends, and was an extreme loser.
Someone who has no friends and tries to purposely fit themselves in with people who hate them.
Mario: (In a nerdy ass voice) Ohhh hey guys! You are all my favourite buddies!
(Everyone leaves as soon as Mario arrives)
Tiene: (To the others as they are leaving) He is such a loser. Him and his brother, mark, are such losers and have no friends.
A looser who can't spell "looser"
Da'vid is such a looser, he spells it loser.
Not Milos
A: Hey that dude is such a loser.
B: That can’t be true, his name is Milos.