"How I Met Your Mother" previews its upcoming episode via a clip which highlights Ted's unsuccessful date with his much younger girlfriend. Played by "Pretty Little Liars" star Ashley Benson, Carly who is over a decade younger than Ted thinks he's much older than he actually is and somehow still admires him.
Ted learns that he has nothing in common with Carly, who speaks things he doesn't understand. Though so, Barney begs Ted to continue seeing his much wilder girlfriend...until he learns who she is.
"Ring Up" will air Monday, January 21 at 8 P.M. on CBS. Also in the episode, Robin must adjust to the power of the bling and her new status as an engaged woman.
Prior to Benson, another "PLL" star Lucy Hale guest starred as Robin's little sister, Katie Scherbatsky, in 2007.