A mug can Mean like oh your a mug or I drank my tea out of a mug the mug you drink tea out of is a bigger version of a tea cup and the oh your a mug version is like I got mugged as in someone stole my money
Being a mug , OG mugbone , or bumscrub is being in the act of doing something that is either silly, fake, weird, or fucked up. It is also used to poke fun between friends.