Last year for my twin boys' 6th birthday bowling party, I made my own t-shirts. I purchased inexpensive tshirts and on the computer created an iron on transfer for the back of the shirt w/ bowling pins and a bowling ball.. It read " Pin Pals" and listed all 8 children in attendance's names on each pin and the bottom read " Meet Me in the Alley" w/ the date.  On the front of the shirt, on the left chest, was a small bowling alley with each child's name on their shirt. When the guests arrive, each boy put on their tshirt over their shirt and they looked like a real bowling team.  It also was a great way to get to know everyone's name.  The parents loved the idea.  My boys still wear their shirts and it is a great reminder of their fun bowling party. We also gave a goodie bag w/ a mini bowling set, mini gumball machine, and other bowling/ball related items.