To Touch Cloth is to have one's poo-poo touch your underpants and leave a stain. It it's slightly more high brow than just to say "UGH I shat my boxers blud."
Ryan: Oh No I can feel my poo touching my lovely new y-front for the charity bin.
When you soil your underpants due to an unexpected shart.
Please note that this is the extreme case of a shart in which the fecal matter explodes beyond the crevice of your butt crack and makes contact with your undergarments.
Harold pushed his fart out so hard that the mud touched the cloth. His wife regrets making the beanburritos.