Ding Dong!  
A ram! Come in, ram.
Come in and sit a bit.
Ding dong!
A rat! Come in, rat!
Come in, rat, and sit a bit.
Can a rat fit in?
Yes, a rat can fit.
A ram! Come in, ram.
Can a ram fit in?  
Can a ram sit a bit?
A ram can fit and sit a bit.
A pig! Come in!
Pig, come in.   
Come in and sit a bit.
Come in and sit.