Joe Sixpack
An average man, typically of the working class. My brother's just your typical guy, a real Joe Sixpack—you can find him watching a sporting event in a bar after work pretty much any night of the week.
Joe Six-Pack
A name for an average, usually lower-middle-class, man, who enjoys drinking beer (which can be bought packages of six—hence "six pack"). Yeah, but those aren't the kinds of political issues that interest Joe Six-Pack, OK?