Ignore the other definition about a hubristic dullard, and say it out loud - it's catchy!
Monty: Baha - rabbit food I say! Now, chocolate trifle is tatsy... er, tatsier
Ramsay: That is one fine tatsy ass!
A stupid, dumb, or arrogant person
( Plural - "tatsies" )
Stupid, dumb, or arrogant
That guy is so tatsy - he's constantly bragging about how smart he is in school, yet he's never made an A!