71-year-old Betsey Johnson — SORRY, GOTTA SPLIT

She”s 71 years old … but that didn”t stop legendary designer Betsey Johnson from doing a FULL SPLIT on stage Wednesday at Fashion Week … while wearing a hilarious pair of pink briefs.

Who knows, maybe she”s got an extremely high threshold for pain … she is holding what appears to be a prescription pill bottle after all.

Either way. Respect.