Please find the most appropriate rhyme, and furnish a clever last line for the following limericks: 

Agronomists in cold Montana
crossed the pine tree and banana
and those hybrid trees
survived winter freeze

Sam told his wife, she was chubby
and sorry he was her hubby
his candor caused him
an ending quite grim

When you want to be gymnastic
don't wear pants with loose elastic
for some careless chance
could rob you of pants