It's a funny version of the "Shiny happy people" song of R.E.M. The band played this song in "Sesame street". R.E.M. was an American rock band from Athens, Georgia, that was formed in 1980.

Original version:  Shiny Happy People (R.E.M.)

Shiny happy people laughing

Meet me in the crowd, people, people

Throw your love around, love me, love me

Take it into town, happy, happy

Put it in the ground where the flowers grow 

Gold and silver shine

Shiny happy people holding hands

Shiny happy people holding hands

Shiny happy people laughing 

Everyone around, love them, love them

Put it in your hands, take it, take it

There's no time to cry, happy, happy

Put it in your heart where tomorrow shines

Gold and silver shine

Shiny happy people holding hands

Shiny happy people holding hands

Shiny happy people laughing 

Whoa, here we go

Shiny happy people holding hands

Shiny happy people holding hands

Shiny happy people laughing

Shiny happy people holding hands

Shiny happy people holding hands

Shiny happy people laughing

Shiny happy people holding hands

Shiny happy people holding hands

Shiny happy people laughing

Shiny happy people holding hands

People, happy people

People

Furry happy monsters laughing

Monsters having fun
Happy, happy
See them jump and run
Happy, happy
Laughing all the while
Cheerful, cheerful
Flashing a big smile
That's a perfect sign

That they're feeling fine

Furry, happy monsters feeling glad
Furry, happy monsters feeling glad
Furry, happy monsters laughing

Something has gone wrong
Sighing, sighing
Faces have turned long
Crying, crying
Hear them sob and whine
Tearful, tearful
That's a real good sign
That they're feeling glum

Sad, sad times have come

Furry sobbing monsters feeling sad
Furry sobbing monsters feeling sad
Furry sobbing monsters crying

Come on, monsters! You don't have to cry, we can be happy!

Furry happy monsters feeling glad
Furry happy monsters feeling glad
Furry happy monsters laughing
Furry sobbing monsters feeling sad
Furry sobbing monsters feeling sad
Furry sobbing monsters crying
Furry happy monsters feeling glad
Furry happy monsters feeling glad
Furry happy monsters laughing
Monsters, happy monsters
Happy monsters
Monsters, happy monsters
Happy monsters
Monsters, happy monsters
Happy monsters

FURRY: Covered with fur (hair) everywhere

FLASHING A BIG SMILE= To flash a smile is to show a smile (when people can see your smile)

GLAD=Happy

SIGHING= To sigh is to let out one's breath with some noise, usually to show you are sad or nostalgic or in love...

SOB= Lament; to weep with a catching of the breath or in sudden, short gasps.

WHINE= To make a long, usually nasal, complaining sound, like when weeping.

TEARFUL= With tears in your eyes.

GLUM= sad and in low spirits, depressing.

It´s a easy and fun song.
Singer Michael Stipe spoke it in the song: We can be happy!