Capsicum
The fruit of most species of Capsicum contains capsaicin. It is a defence against herbivory. Capsaicin is a chemical that can produce a strong burning sensation in the mouth (and anus) of the unaccustomed eater. Most mammals find this unpleasant, but birds are unaffected.  The plants developed the secretion of capsaicin to protect the fruit from being eaten by mammals. At the same time, the bright colors attract birds. These birds will spread the seeds.