Dee Sinks in a Bog

"Dee Sinks in a Bog" is the seventh episode of the fifteenth season of It's Always Sunny in Philadelphia.

Synopsis
Guided by a young priest, Mac spends a day at the seminary to truly understand what it takes to become a priest. Dennis and Frank plan an elaborate trap at the castle to humiliate Charlie's pen pal. Dee prepares for a date with an Irish doctor, only to find herself sinking in a bog. Having learned of his pen pal's true identity, Charlie bonds with him and makes a choice that will forever change the Gang.

Starring

 * Charlie Day as Charlie Kelly
 * Glenn Howerton as Dennis Reynolds
 * Rob McElhenney as Mac
 * Kaitlin Olson as Dee Reynolds
 * Danny DeVito as Frank Reynolds

Special Guest Star

 * Colm Meaney as Shelley Kelly

Guest Starring

 * Mary Elizabeth Ellis as Waitress

Guest Starring

 * Mark Prendergast as Gus

Co-Starring

 * Tom Archdeacon as Dr. O'Shaunessy

Trivia

 * "Dee Gets Stuck in a Bog" was the original title for this episode.
 * Dee apparently correctly guessed the Waitress' real name sometime offscreen during her listing "every name on the planet".