Remember, it's all fun and games until someone whips out an ax...
Do they still involve blood-feuds?
No no, drinking games don't start blood feuds (although Egill did once deliberately barf on some guy's face during one just to make a point). Things that DO start blood feuds are f.ex.
- disagreement over seating order (Brennu-Njáls saga)
- a fancy hat (well ok, maybe the hat was just the first hint of what was to come and the real feud started by blocking people from using their own toilet) (Laxdæla saga)
- Haraldur Fairhair being present. Seriously the most dramatic king I've ever read of. (Egils saga)
- insisting on pooping on temple grounds (Eyrbyggja saga)
- annnd sometimes plain old killing someone (Gísla saga Súrssonar)