Flag of Japan

When you fuck a chick on her period and blood leaks onto white sheets creating a Japanese flag lookalike.

B: Shit! Your bed sheet looks like a giant flag of Japan!
J: Yeah, Rachel is on her period and I fucked her on the bed last night.

Flag of Japan

Slang

Description of a white person's bottom following a period of gastric distress, often following a curry

1
"Mate, how was the curry last night?"
"Great but my arse is like the Flag of Japan this morning"