The act of clenching your butt-cheeks together to stop or halt defecation. This usually results in sweating, lack of movement, clenched jaw and praying.
I knew I wasn't going to make it to the bathroom in time, so I had to start puckerbutting in order to hold it in.
My very greedy brother Jeffrey stole my peanut butter and had his dog perform a Puggernutter on him during his extremely long commute from Barnegat to Elizabeth.