It is a derogatory term used against people from the future. The term gooback came from the fact that when they travel thru the time portal a side affect causes them to be covered in goo, hence the term gooback.
Person who arrived via time portal from the year 3045 to escape the harsh conditions of that era. A blend of all present-day races and speaks a language that is a mixture of English, Turkish, Chinese etc. Tends to work for extremely low wages, displacing hard-working present day Americans. Time-traveling had left them with goo on their backs. See also wetback.
("wentback" would have made sense without the need for goo.)
"That mother-fucking gooback took my $140K-a-year logistics job for 90 centsan hour!"
A friend named joe who usually wakes up after a heavy night of drinking, on the floor with the back of his sweatshirt covered in a semen appearing substance.