Shit Boogers are found the morning after a night of having your nose in a girls butthole. When you sneeze or pick your nose in the morning and find a little piece of poo....this is a shit booger. CONGRATS! You just got your first case of shit boogers!
I woke up this morning and remembered that I 69'd with my girlfriend last night. While engaged in the act, I stuck my nose up her butthole for some odd reason. Then I sneezed out some Shit Boogers!