A mountain bike or mountain bicycle (abbreviated MTB) is a bicycle created for off-road cycling. This activity includes traversing of rocks and washouts, and steep declines, on dirt trails, logging roads, and other unpaved environments—activities usually called mountain biking.
In its most basic form, pre-flight beer stretching is a natural and instinctive activity. One will stretch before and after drinking beer in the airport to prevent injury before boarding the plane.