A phrase exclaimed when spotting a woman in a bikini or
tight-fighting pants who has a particularly noticeable thigh
gap--the
space between her inner thighs, directly below her pussy.
Thigh gaps are measured in
male fingers, as in the number of fingers you could fit into the thigh gap. "Mind the gap" exclamations should be reserved for thigh-gaps of no fewer than
four or five fingers.
Thigh gaps of this severity mostly happen to anorexics or girls whose thighs have been freakishly separated from being ploughed.
The phrase itself is derived from an announcement stated over the PA'
s on the London tubes (subway), which says in full "Mind the gap between the train and the platform."