An alternative version reads:
Kermit:It's the Muppet Show with our Very Special Guest Star, ...
Females:It's time to play the music
It's time to light the lights
t's time to meet the Muppets on the Muppet Show tonight.
Males: It's time to put on makeup
It's time to dress up right
It's time to raise the curtain on the Muppet Show tonight.
Waldorf: Why do we always come here
Statler: I guess we'll never know
Waldorf: It's like a kind of torture
Both: To have to watch the show
[NB I remember seeing a few episodes with this version, but usually I remember it being sung by Kermit with the words in davidthedark's answer]
Muppets: And now let's get things started
Audience: Why don't you get things started
Kermit: It's time to get things started
Muppets: On the most sensational inspirational celebrational Muppetational
This is what we call the Muppet Show!