In Britain, if you buy a packet of crisps (aka chips) at the pub, it is in fact the law to share them with the rest of your table-mates. To not share is considered the height of rudeness and certainly a punishable offence.
Sharing the crisps in itself is an art form. You don't just rip the bag open and pass it around. Oh no dear reader, you must expertly peel apart the bag's corners creating a foil tray in which everyone can partake with dignity.