LONDON  Michael O’Leary, chief executive of the European budget airline Ryanair, was discussing his new scheme to charge passengers to go to the bathroom.

Most passengers  the “discretionary toilet visitors,” as he calls them  would eventually forgo in-flight bathroom use altogether, he predicted. Which is good, because he would also like to reduce the number of bathrooms per plane, to one.

What if the plane were stricken by some nasty, effluent illness, like food poisoning?

A snorting noise wafted over from the chair where Mr. O’Leary was sitting. “We don’t serve enough food for everybody to get food poisoning,” he said.

At 48, the quick-talking, blue-jean-wearing Mr. O’Leary is one of the most successful businessmen in Ireland, presiding over an airline that is, remarkably, flourishing in a brutal climate for airlines (and most other businesses). He is known for thick-skinned aggression, outrageous public statements and an implacable belief that short-haul airline passengers will endure nearly every imaginable indignity, as long as the tickets are cheap and the planes are on time.