Alyson Hannigan

Episode 1.20 "Best Prom Ever" - A special venue that Lily and Marshall had their eyes on to get married at has opened up a date — but it’s in just two months. They decide to go for it, but planning the wedding in just two months starts to get Lily stressed. They need a band for the wedding, and the one that Marshall wants is available. Lily hasn’t heard them, however, and needs to see the band before she approves. The band is playing at a high school prom, so the gang tries to sneak in. It’s special for Robin, who never went to her prom.