Maybe you should use google and do a little research.
Spanish fly - Wikipedia, the free encyclopedia
wasn't that easy.
I'm surprised that anyone would even consider such a thing since the invention of Viagra et al.
Ingesting the crushed body parts of a "Blister Beetle" to irritate your penis and hopefully induce an erection seems like a rather stupid idea when you read the parts about painful urination, blood in urine kidney damage and permanent damage to the genitals (they might mean your dick).
Remember BLISTER (on the inside of your cock) beetle.
OUCH!