When a girl thinks she may be pregnant, and takes a common drugstore pregnancy test to find out that she is not, in fact, pregnant. "Pink" is derived from the colours of the indicator stripes on the test, and "scare" is obvious as this is scary shit.
"Tanya slept with that guy last week and today she had a pink scare."
A dirty Russian vagina that is infected with communism.
I went down on Tatyana's pink scare and came up smelling like the gulags.