Fun 4 Hours, Frederick

One look at Chuggy Choo-Choo Train makes it clear that Fun 4 Hours uses the term bounce house loosely. Kids bust through one of the doors into a linear stretch of bouncy floors and cushy slides, streaming out the other end for another go-around.

Chuggy is just one of the inflatables that Fun 4 Hours brings to clients' backyards. Its staff also sets up castles, ball ponds, and even dinosaur-shaped bouncers. That's not to mention all the other party gear they can bring for bashes: canopy tents, tables and linens, digital-photo booths, popcorn or hot-dog makers, and even materials for crafts.