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.
by csisok86 December 30, 2016
Get the Flag of Japan mug.
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"
by Rawhyde July 29, 2017
Get the Flag of Japan mug.