First thing I would do is have the guy that handed me that bill arrested for forgery!
Then I would moan and groan about it not being real.
On the other hand if it was a certified check, I would invest half of it in something safe, use the other half to buy a summer home in England and a winter home somewhere in the Yucatan. Not sure where exactly, but it would be somewhere convenient to my favorite places. Pay off my mortgage in my Spring and fall house here in the states, retire and try and live off the interest and my retirement.
Oh and buy a fast sports car (dating young women is just too expensive
)