If you are hosting a Halloween party or just simply want to spruce up your bathroom for the season, there are several things you can do. These are just a starting point, so feel free to expand on them and make them your own.
For those who are planning on putting some decorations up to leave there for the rest of the season, it is best to stick with ones that are unobtrusive. You can put stickers of spiders on the mirror, hang orange towels instead of your usual color, or find a festive soap dispenser. You could also put a fall scented candle on the counter or some small gourds in a basket. Avoid using cotton webbing to mimic spider webs in the bathroom, especially if it has a shower. The dampness will cause them to stick, and they can clog drains if they are rinsed down.
If you are decorating for a party and hope to get a few spooks, there are some more drastic decorations you can put up. Hang a spider or bat from the ceiling that your guests will walk into when they enter the bathroom. Hide a spider or snake in the tissue box so it flies out when they grab a tissue. Use the soap as a means to cause fright. Fill a clear soap dispenser with orange soap, and stick some plastic bugs inside. If you use bar soap, you may be able to find some Halloween themed bars. Since the light will probably be off in the bathroom when it is not being used, find a light sensitive device to spook your guests. When they turn on the lights, it will activate and make noise or flash other lights.
When it comes to decorating the bathroom, it is best to avoid decorating around the plumbing. Putting things in the toilet, sink, or tub can clog the drain or compromise the efficiency. This goes for webbing or plastic pieces. Also, make sure that the decorations you are using are able to get slightly damp if it is a full bathroom.
The bathroom is often overlooked when decorating for a party. While you can ignore the kitchen, bedrooms, or other rooms the guests will not see, the bathroom is one room that will certainly be used. Continue the festivities in the bathroom to keep a smile on their faces for the duration of the party.