Vikings in a comic strip.  I was close to doing a joke about Hagar the Horrible, about some of the darker aspects of Vikinghood which the strip has yet to deal with, but nothing was gelling.  Instead I did a do-over and just gave them some aspect of tension to deal with, and let the dialogue emerge.  It took a lot of rewriting to get it to anything resembling funny, though, and the “you suck” bookends were kind of a lame little way to add a laugh to the overall recipe.