The happy coincidence of accidentally leaving your pants fly open, and the corner of your shirt poking out of your fly in such a way so as to form a shirt dick that may be mistaken for your very own penis. A largely unfortunate and unintentional occurrence. Worse when wearing skin tone coloured shirts.
I was in such a hurry this morning that I forgot to do up my fly. To add insult to injury, after a morning of travelling on public transport and polite conversation with customers, I looked down to discover not only my open fly, but that I was also sporting a rather impressive shirt dick.