Hi Samantha, welcome to planDisney!
I hope you were able to secure tickets to
Oogie Boogie Bash – A Disney Halloween Party! I just checked and tickets are currently sold out. Oogie Boogie Bash is one of the most anticipated events each year, and tickets typically sell out very quickly. But if you were able to secure tickets, you're in for a TREAT!
With tickets to this event, you'll have early admission into
Disney California Adventure Park starting at 3:00 p.m. (California time), no theme park reservation required! The event will officially start at 6:00 p.m. through 11:00 p.m. Once the event starts, you'll be able to enjoy the immersive treat trails, various character experiences, a frightfully fun parade, Mickey's trick and treat show, and so much more!
But back to your main question, as long as your costume falls within the
Costume Guidelines, you should be good to go! I scanned the guidelines, and did not see any mention of small face paint. I do however see that costume masks of any kind may NOT be worn, but hopefully small face pain would not be categorized as a costume mask.
I hope this helps, and if you have any other questions, please visit us again!
See ya real soon!
Jin