Are you fit as a flea?

Hand on my heart, I do not like fleas. Even more, I absolutely detest them; in my opinion, they are nasty little insects who survive by drinking blood of mammals and birds.

On the other hand, I love keeping fit and exercising as it gives you positive mental and physical energy, but why would anyone put fleas and being fit together in one sentence, never mind the same expression?

According to various etymological dictionaries, the word ‘flea’ has been in use since the 8th century, however the expression itself has been used since the late 19th century to describe a healthy and active person in a very good physical condition. So next time if anyone says that you are fit as a flea, take it as a compliment!

Another expression with the word ‘flea’ is ‘to get a flea in one’s ear’, in other words, to be told off or rejected. The pain of being criticised or not accepted is so strong that it is associated with the discomfort experienced by dogs and cats being hurt by fleas biting and moving inside their ears.