Based on the racoon streamer Goob554, the word is a combination of the words Goober and Girly pop. The term is used in reference to someone who is slaying but in a feral or silly goose way.
Similar to the term 'Girly pop' Goobie Pop implies a level of slay factor in what one is doing. However it also implies that this slay has feral or silly goose energy to it thus making it goobie pop.
Indiscriminately firing bullets into your city of residence just for the fun of it. A City Pop demonstrates your dominance over rival gangs, neighbors, law enforcement, and the law as a whole. City Pops are usually performed as casually as showering or brushing one’s teeth.
"Eh bruh, Mayor Johnson veto'd dat ShotSpotter again. Ya know what that means?! City Pops! City Pops! City Pops! City Pops!"