"I Do" (Written by Trevor Penick)
"I do, I do
Think it's time for me and you
To sit back and talk about what we wanna do
Do we wanna stay together forever
'Cause I do
I do, I do
Wanna talk about kids and a car
White picket fence and a yard
Do we wanna walk down the aisle together
'Cause I do
Mm mm"
These are just the lyrics to the part Trev was singing on MTB.  :)