Have Matt and some of the other guys do a few Primary songs in a "Beastie Boys" style–where each guy takes a turn singing one line but all three sing the word that rhymes.

Then you could sing the following:

Priesty Boy 1: Book of Mormon stories that my teacher tells to *ME*

Priesty Boy 2: All about the Lamanites in ancient histo-*RY*

Priesty Boy 3: Long ago there their fathers came from far across the *SEA*

All: Book of Mormon stories that my teacher tells to me.

(Then seamlessly transition to next song using same beat)

Priesty Boy 1: I looked out the window and what did I *SEE*

Priesty Boy 2: Pop corn popping on the apricot *TREE*

Priesty Boy 3: Spring has brought me such a nice su-*PRISE*

All: Pop corn popping right before my eyes.

This type of skit takes literally no practice and can be memorized in minutes.