The ushers thought it would be fun to have glow-sticks at the wedding reception, so the night before the wedding they went to the store and bought a ton of those glow bracelets that link together... and I had no idea.
About an hour into the dance I started to see glowing things everywhere - it looked awesome. Everyone was getting into it. My grandma was wearing a necklace. My little cousins were gathering up bunches of bracelets. Some of my parents friends were wearing them as earings or hooking them through their suit button holes. It was hillarious and a ton of fun!
If you're looking for an inexpensive fun suprise for guests, they sell packs of 10 for $1 at Michaels and I think Target too.