it basically means shut up

A dick because mayo looks like cum, and cum comes out of dick.

The practise of spreading mayonnaise around the edge of a pate in a restaurant so that when the waiter comes to pick up the plate s/he gets mayo on their hand.

its a sandwich which just egg and mayonnaise

a stupid, ignorant, and probably racist white person

Exceptionally large hands in proportion to the rest of the body, a common genetic abnormality occurring in the natives of an area of western Ireland called Mayo. The reason for the mutation is believed to have come from the natives love for finding potatoes, throwing turf at strangers and means that the area breeds some of the finest volleyball players in the third world.