A frog. It croaks every night.
A cosh(x/a)
They both love using the toilet right after it's been cleaned.
They always want to play leap frog with him
Reddit
A kid with cerebral palsy living in Australia
Downtown Abby
A lukeworm.
Duck.
Someone who lies awake at night if there really is a dog.
A person who stays up all night wondering if there is a dog!
A cat has nine lives, but a frog croaks every night.
He simply croaked!