In the Roger Miller episode of The Muppet Show, the theater is swept with an epidemic of "Cluckitus", a disease that causes anyone infected to turn into a chicken. Kermit, worried that the news of this affliction may upset the guest star, orders that the epidemic be kept secret (an impossible feat, as Muppets-turned-chickens retain their normal voices). This leads to a specific denial from Robin:
Robin: We aren't turning into chickens!
Robin's denial became even more suspicious just a minute later, when he caught it.