Perfect Gift for Ten Year Old Boy

My nephew will turn 10 years old soon, so they had his birthday party this past weekend.  Activities included Nerf gun wars, and from what I'm told, the weaponry advancements now include battery power, giving the capacity to launch darts up to 100 feet! Water-pellet guns are also a new addition to the arsenal, which do indeed leave a welt.  We only had the suction-cup dart guns when we were kids -- not much distance on those.

A neighbor stopped by the kiddie birthday party Saturday to drop off my nephew's gift, which was a Daisy slingshot and marbles.  That gift was hidden by my sister, until we stopped by yesterday.  What, one slingshot and six little boys - what could go wrong?

The slingshot at the birthday party reminds me of the Christmas when my mom gave my then 6 year old nephew a tub of cotton candy and three slingshot monkeys.  Again, what could go wrong? My 18 year old niece was shot in the eye with a flying monkey within three minutes of my nephew opening his gift.  I never saw the monkeys again...

What's the best toy YOU'VE ever owned?