lucky charm ass

When you haven't done laundry in weeks, and the only underwear you left have to wear are back-of-the-drawer obnoxiously patterned/colored underwear that was likely purchased in your prepubescent years. When you sport such underwear, you at this time have what is known as a "lucky charm ass".

Her outfit is stunning, and it was pretty appalling when she bent over and I saw she had neon green unicorn underwear, a lucky charm ass if i'd ever seen one.

My one deal breaker is if the girl I'm hooking up with has a lucky charm ass. I want to feel like she's my age, not 12.