according to wikipedia, irony is a literary or rhetorical device, in which there is an incongruity or discordance between what one says or does and what one means or what is generally understood.

• a billboard about your dog being a co-pilot posted in the exact place where a gentleman and his dog were killed in a car accident when the white german shepherd jumped in his owner's lap while driving
• your husband being in an accident causing him to be a paraplegic and your full-time job is physical therapy for people with paralysis
• your husband needing an colostomy bag and your full-time job is working with in the urology/ostomy division of a medical products company