A pigeon poop boutonniere is what you're likely to get from sitting on the church steps while waiting for the service to begin. Church steeples and belfries are notorious pigeon roosts. A pigeon aroused from its roost is unlikely to control its bowels and routinely poops to shed unnecessary take-off weight.
My brother got a pigeon poop boutonniere for his brand new suit last Sunday.
The flowers men wear to dances. The male equivalent of a corsage. I know you should wear one to the Homecoming dance, but other than that I'm unsure if you should to wear it to other dances.