Verbal irony is when what is said is the opposite of the literal meaning. One type of verbal irony is sarcasm, where the speaker says the opposite of what he or she means in order to show contempt or mock. Other types of verbal irony include overstatement (or exaggeration) and understatement.
Thanks for A2A. There are two excellent, well-informed answers here, so I'll just try to simplify. Dr. Falconer is of course correct; pre-weaning age (about 9 weeks or younger) kittens can drink cow's milk, or any milk. Neonates are not lactose intolerant; this develops gradually with age.
Cats are biologically made with two sets of teeth: milk teeth and adult teeth. Kittens are born with their milk teeth, which allow them to latch onto the nipple and are only made to comfortably handle mother's milk. These teeth are barely strong enough to chew food and typically fall out around 6 months of age.