Oshago is an old Jamaican slang used to replace certain phrases that are exclaimed and or just completely outrageous. Phrases like "oh fuck!", "no way!", "shit", "that's just crazy!" or "that's so fucking awesome!". Today it can be a new way of expression to show we feel about something in the moment that is just so ridiculous, out of the ordinary or something just very cool.

the thing that you don’t have when you’re phones percentage is over 20