You could also call these penis pants. They are too big, and bunch up in the crotch - sometimes the extra fabric tents, and can look like your 'packing'...and that isn't a good look :). This was hard to get a pic of, since it is a 3 dimensional thing that I am trying to show here in 1-d...
This is an example of pants that are too small. Note the pull through the hip - say cheese!