The episode you are referring to is titled . It originally aired on April 1, 1998, as the first episode of Season 2.
This episode is famously known for being an played on the audience. Fans had waited four weeks to find out the identity of Eric Cartman's father (following the Season 1 cliffhanger "Cartman's Mom Is a Dirty Slut"), but creators Trey Parker and Matt Stone instead aired this standalone special featuring only the fictional Canadian duo. Episode Summary [S2E1] Terrance & Phillip in
: Terrance and Phillip must travel to Iraq to rescue Sally. While they are away, their arch-enemy, Scott, inadvertently helps Saddam Hussein invade and take over Canada. The duo must then use their signature "fart-based" humor to defeat the dictator and save their country. The episode you are referring to is titled
: Terrance, Phillip, Sally (Terrance's daughter with Celine Dion), Scott "the Dick," and Saddam Hussein. Fans had waited four weeks to find out