Sadowski replaces Ryan Devlin, who starred in the pilot as Shatner's son -- in a role loosely based on Justin Halperin, the creator of the popular "Shit My Dad Says" Twitter feed.
Sadowski was a cast member of NBC's recent Larry Charles comedy pilot. His other credits include guest spots on "Chuck" and "House," as well as a regular role on "Miss/Guided" and a recurring gig on "Terminator: The Sarah Connor Chronicles."
Sadowski joins a cast that also includes Nicole Sullivan and Will Sasso. "S#*!" (that's pronounced "Bleep") stars Shatner as a cranky dad prone to quips of the 140-character-or-less variety. His world is rocked when his young son -- now played by Sadowski -- is forced to move back home due to a lack of funds.
Warner Bros. TV is behind the show, which landed the plum Thursday 8:30 p.m. slot behind hit "The Big Bang Theory." David Kohan and Max Mutchnick are the exec producers.
As for Sadowski, the thesp's other credits include TV skeins "American Dreams" and "NCIS," as well as the features "Friday the 13th," "The Goods: Live Hard, Sell Hard" and "Live Free or Die Hard."