On Thursday, CBS will air the penultimate episode of "Two and a Half Men" in which Alan will propose and Gretchen will force him to confess his true identity to Larry.

In the official trailer for the upcoming episode, which is titled "Dial 1-900-MIX-A-LOT," Walden and Jenny are seen sitting in a private jet. Barry also appears on the plane, saying "Guess who just joined the mile high club?" In response, Walden, quips "It doesn't count when you do it to yourself."

Alan is going to come clean about his alter ego, "Jeff Strongman," to Larry, confessing that he used to be with Larry's now-fiancé, Lyndsey, and that she has cheated on him a number of times with Alan since they got together.

According to BroadwayWorld.com, the synopsis for Episode 11.21 states that "Alan's girlfriend, Gretchen, insists he confess his true identity to Larry. Meanwhile, Walden goes on a road trip with Jenny and Barry to see his first car."

CBS recently announced that country singer Brad Paisley has signed on to guest star opposite his real-life wife Kimberly Williams-Paisley in the Season 11 finale on May 8, reports TV Guide. Details about Paisley's role on the comedy series have yet to be disclosed. His wife, however, plays Alan's new love interest, Gretchen. Things are moving fast for Gretchen and Alan, which will lead up to a big moment in the final episode. However, given Alan's misfortune, it's safe to bet that Paisley's appearance will stir things up in his love life.

"Two and a Half Men" S11E21, "Dial 1-900-MIX-A-LOT," airs on Thursday, May 1 at 9 p.m. EDT on CBS.

Watch the trailer video below.