Used to describe an event, object or person which is of little importance. Stems from the fact that chickens (at least those bred as food) have
wings but can't fly, rendering the
wings unimportant. Can be used in place of a reassuring "don't worry about it" statement but often used as a
sarcastic retort suggesting that which is being described is really not as important as the person saying it believes
Dave: Man I can't beleive I have to work on Saturday
Steve: Hey man, it ain't no thing but a
chicken wing
OR
Dave: I got toally carved up by some d*ckhead white van at the roundabout
Steve: So? It ain't no thing but a
chicken wing