How about a Bossel tour along the Diemel cycle path?
 
The aim of the game is to throw a bowling ball, one ball per team, over a predetermined distance (e.g. 1 km) with as few throws as possible. The balls must come to a standstill on the path or the adjacent bank. Balls that enter ditches or fenced-off meadows etc. will be penalized with a penalty point or, in the stricter version, with a "handicap drink".
 
Extremely good fun on a sociable hike.