A squid beak is similar to a camel toe
. It is the visible sign of a woman wearing underwear and trousers which are too tight.
Squid beak is used when the woman in question is a horrid minger and no-one wants to see her revolting flange.
Check out that fat minger. She's got a massive smelly squid beak and she doesn't know that her undercarriage is on show.