Dressing up horse for Halloween Party?

Me and my friend want to dress up my horse for a Halloween party and we figured we could go with a slumber party theme. We were going to paint his nails :), use a quilt as a saddle pad, and we could dress in pjs and bathrobes and carry stuffed animals. We were also trying to incorperate other sleepover traditions like watcfhing movies, or eating food, but we don't know exactly how to do it? any suggestions?