A dingus con is the king of dinguses. AKA the king of a person who is goofy, akward, and clumsy. A dingus con makes you laugh because of the stupid things they do.
You and your friend are walking down the street talking. Your friend does not see the trash can in front of them because they are speaking to you and they topple it, spilling its contents everywhere.
You say, "You dingus CON!!!!"