I've been thinking a lot about those half-pumpkins that you see around Halloween (they're a cousin to candy corn; one of my perennial favorites). I'm planning to pipe an icing version of those, of course, but I thought I'd better hold off and work on something more seasonal: a pineapple. All you need to pipe a little half-pineapple that would look darling on a cupcake or any small dessert are royal icing in green and yellow (or a more realistic color), a dusting pouch filled with a 50/50 mix of powdered sugar and cornstarch, parchment paper squares, round tips #12 and #5, and oval tip #55 by Ateco.
Start by piping a shape reminiscent of a Hershey's Kiss in the middle of a parchment square. Hold the #12 tip just above the surface, squeeze until the base is about the size of a dime, then draw the tip slowly upward while maintaining even pressure. Stop pressure and pull away the tip when the shape is about 3/4" high. Touch a fingertip to the dusting pouch and tap the peak into the rounded shape you see here:
SpongeBob SquarePants-themed cupcakes; anyplace a little tropical accent is appropriate.