91色情片

Light ale: A strange phenomenon caused much comment at a barbecue this summer. To keep the cans of beer cool they were placed in a large plastic dustbin filled with cold water. Strangely some cans remained on the bottom of the bin while others floated on the surface of the water. There were more submerged than floating cans, but this behaviour was not confined to any particular brand. What could be the reason for this?