Caffeine is the stimulant in coffee and tea!
"Caffeine is a bitter, white crystalline xanthine alkaloid and a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants, as well as enhancing the reward memory of pollinators."
--http://en.wikipedia.org/wiki/Caffeine
Model created using VMD:
http://www.ks.uiuc.edu/Research/vmd/

Successfully printed by a Replicator 2 in PLA using MakerWare(TM) 2.4.1.24, standard resolution (3 shells, 25% infill), with raft and supports.
Different representations are provided as a guide to coloring the molecule by hand.