It's the moment we've been waiting for: The gathering of the Tammys on 'Parks and Recreation' (Thurs., Sept. 29, 8:30PM ET on NBC).

Yep, in 'Ron and Tammys,' Tammy 2 (Megan Mullally), Tammy 1 (Patricia Clarkson) and Tammy 0 (Paula Pell) will all pop up to cause havoc in Ron Swanson's life.

Things deteriorate rapidly and can only be solved via a very special drink-off! The stakes are high and the ending may surprise you.

What else should you expect? Patricia Clarkson being awesome and then some!

Paula Pell, known for her writing duties on '30 Rock' and 'Saturday Night Live,' has been cast as Ron Swanson's (Nick Offerman) mother, Tammy, on 'Parks and Recreation.'

According to TV Guide, Pell, who plays Paula Hornberger on '30 Rock,' will appear as Tammy Zero early in Season 4.

Patricia Clarkson will appear in Season 4 as Tammy 1, Ron's first ex-wife. Megan Mullally, Offerman's real-life wife, has made several appearances as Tammy 2, Ron's second ex-wife named Tammy.

Can Pawnee handle three different Tammys? We'll see on Sept. 22 when 'Parks and Recreation' returns to NBC.

In other casting news ...