Costume: Major League Umpire
It takes a lot to be an MLB umpire: finishing ump school with top honors, years in the minors, a lifetime on the road being away from your family and a bit of luck.
It doesn't take that much to make the uniform, however. All you need is a blue or black polo shirt with a pocket, charcoal- or heather-grey slacks, a computer, printer, scissors and some clear double-sided tape.
First, find some black and white MLB logos, or make them yourself. Print out a three-inch square size graphic, cut it out and place it on the shirt's left breast pocket—if you don't have a pocket, don't worry. You can still go as a base umpire. If you're feeling nitty gritty, print out another logo—this time less than an inch in width—and place it centered on the backside, right below the collar.
You can also print out a black and white number for your right sleeve.
Write down some fake lineups and rosters on two sheets of paper, fold them and place them in your pocket as lineup cards. Add a pen for special effect.
If you happen to be a catcher by day, wear your protective gear on the inside of your ump costume to complete the illusion.