VIDEO: 'How I Met Your Mother' Episode Ends With a Shock

Monday's episode of How I Met Your Mother ended with a dose of harsh reality for Jason Segel's character Marshall Eriksen.

The episode featured a countdown from 50 with a big surprise ending once they got down to 1.

The episode centered on Marshall and Lily (Alyson Hannigan) trying to get pregnant. The couple believed were having fertility problems, but ultimately that was proven not to be the case. (In fact, it was Barney Stinson's (Neil Patrick Harris) doppelganger who revealed that Marshall and Lily were fertile.) Once Marshall found out the good news, he stepped out of local pub MacLaren's to phone his dad with the good news, but things weren't as they seemed.

Happiness turned to sadness as Lily exited the cab (with the number "0001") and told him some news ..