As a fun idea and good practice for those wild solos, for Halloween you can take your instrument and an amp down onto your front porch and make creepy noises while the local kids are trick or treating. Any instrument will do, and it's often good if you are not that familiar with it, that could add to the creepiness.
It's a good time to play with those feedback and delay noises that no one wants you to actually use in songs. Play with all those extreme sounds that hardly ever get any use in your multi effects device.
Elephant and owl hoots similar to those by Adrian Belew are good, and of course any flangy feedback or echo bass. Synthesizers have any number of great sounds available.
Also think horror movie themes. Even a bad rendition of Tubular Bells would work well, or one of your other favorite movie or TV themes. Think, "What would George Romero want to hear?" Anything that sounds evil or mysterious will draw more kids to your house, so you won't have as much leftover candy to get fat on. Add a mic and practice your evil laugh.