More than retarded, retarded to the third degree.
Dude, yo' mama failed the second grade? She must be threetarded!
A word to describe a poor connection to the '3' mobile phone network.
The '3' network is highly disputed among most (including 3 customers) to have the crappiest coverage of all of the UK mobile networks.
Sorry, my signal just cut out. I think my phone's just being Threetarded.