This is the one I've been using for the last 3 years: https://www.amazon.com/gp/product/B006JYHG3U/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

It can hold A LOT of stuff, including beers and other items you want to sneak in. It has a handy rain fly which came in handy a few years ago.