Two Eurovision Song Contest entries have been performed in Sesame Street productions. "Sing Sang Song," Germany's entry from 1976, performed by the Les Humphries Singers, and "Disco Tango," Denmark's 1979 entry by Tommy Seebach.

The German entry was the title track of the disco Sesame Street LP Sing, Sang, Song Singalong. Elmo, Signe and the letter "D" all danced to "Disco Tango" in Sesamgade, the Danish co-production of Sesame Street.

(Fact co-written with @eurovision-facts)

Sources:

Sesamgade. Afsnit 117: En stjerne på dansegulvet. February 14, 2010.

Sing, Sang, Song Singalong. Side one, track one, "Sing, Sang, Song." LP. 1978. (YouTube link).

"Sing, sang, song - Germany 1976 - Eurovision songs with live orchestra." escLIVEmusic1. YouTube. June 9, 2014.

Eurovision songs have snuck their way into the popular children's program Sesame Street many times.

In 1978, a Sesame Street LP was released entitled 'Sing Sang Song Singalong,' which featured the 1976 German Eurovision entry, 'Sing, Sang, Song' by Les Humphries Singers. In 2010, the Danish production of Sesame Street, Sesamgade, aired an episode that featured Elmo dancing to the 1979 Danish entry 'Disco Tango's by Tommy Seebach.

(Fact co-written with @muppet-facts)

[Sources]