Seven lyrics

Oh, there's the doorbell
Let's see who's out there
Oh, it's a seven
Hello, seven
Won't you come in, Seven?
Make yourself at home.

Hey, who's that other guy?
Is that your friend there?
"Oh, that's just Seven"
Another seven
Hello, Seven
Won't you come in as well?
Now who would like some cake?
("I would like some cake.")
("Me too!")

What's that at window?
A whole bunch of sevens
They're coming in now
And there's a lot of them
And down the chimney too
("Hey guys, come on in!")
I bet they want some cake
"We want cake! Where's our cake?"

My house is full of sevens
They're filling up the living room
Sliding down the banister
Talking on the telephone
Inviting over more sevens
("It's a green house at the end of the block")
I'm running out of cake.
"We want cake! Where's our cake?"

My house is full of sevens
"We want cake! Where's our cake?"
Lots and lots of sevens
"We want cake! Where's our cake?"
Many more are stopping by
Sevens add and multiply
There's only way to subtract them:
Let them eat up all the cake

Submitted by Guest

What do you think is the meaning of Seven by They Might Be Giants?