Something so FANTASTICALLY stupid or retarded, it ceases to be fantastic and thus becomes tardtastic! Lengthen the 'A' in tard for a more dramatic effect.
"It's a TARDTASTIC day today!"
"This photocopier is acting completely tardtastic today!"
A word introduced by Universal Studios and Jimmy Fallon that is a combination word of the two words "tram" being the vehicles used to transport people on the Studio Tours Ride in the Universal Studios amusement parks and the word "fantastic"