Mascara mishap

SMEAR

What you might do to eyeliner when rubbing your eyes too hard.

"Smear" fits "mascara mishap" because it directly describes what happens when mascara accidentally spreads or blurs—like when you rub your eyes or it runs from sweat. The word plays on the idea of makeup going wrong, which is a common beauty frustration. It’s a straightforward answer since "smear" is the exact term for that messy, streaky result.