A variation on beer can chicken. I did this with a can of iced tea rather than beer but I don't think it makes that big a difference (my beer can chicken does not taste like beer and this duck did not taste like tea - the flavors come from the rub). Remember roasting duck is not like roasting chicken. The skin of a duck is massively fatty and the meat is dark meat. You need a lot of cooking time and you want the fat to drip out. Piercing the outer layer of skin and long roasting time will accomplish this and will leave you with a crispy delicious skin.