circles on underwear, skivvies or other pantswear that show up and may be the work of aliens (such as Klingons or other off-world groups)
Mikey noticed that every morning when changing his underwear his dog Lucky would immediately start licking the mysterious crap circles that had appeared there.
Running around a campfire or bonfire while farting the whole time, thus producing a circle of crap smell for everyone around the fire to enjoy.
Origin: This weekend camping, crop dusting turned into a crop circle when I dusted everyone around the camp fire which then turned into the crap circle because it smelled like crap