Ideas for painting plastic pumpkin for a Rally for the cure luncheon?

Modern ideas include painting glue in a simple pattern or all over and applying glitter.

Adding masking tape and painting certain areas specific colors - using black and white and leaving an area blank (pumpkin orange).

Drawing geometric patterns on it with a Sharpie.

Writing on a pumpkin in modern calligraphy.

Inexpensive, fast, showy, not messy, and little cleanup : get a colorful variety of thrift store hats, childrens caps, sunhats, character hats, etc. Stuff with newspaper, plastic and bamboo skewers to make it seem like the "pumpkin head" is larger than it really is. After Halloween, the hats can be re-donated back to the thrift store if you don't want to keep them until next year.

What is the theme or color scheme of the luncheon? Fall related?

Use two pumpkins and make something similar to this cute idea I saw online. instead of covering with fabric, you could paint them pink and add "pasties" on the front....or paint them as if they are wearing a bikini top or something like that. If you are with a group that has a sense of humor, you could turn them on their side with the stems facing forward and paint the stems a slightly darker shade of pink to represent nipples. Just an idea....hope I don't offend anyone! :)