Slang used all the time by Almost Everyone
"Maje" is used to refer to your friends or anyone in a casual way. It can also be used as an insult depending on the context.
"Maje, ¿dónde estás?" "No seás maje"
"Dude, where are you?" "Don't be fool"
3 out of 7 Spanish, Castilian speakers have heard this