Bozo the Clown is a franchised clown character created for children's entertainment in 1946, and is portrayed by various local performers in different markets.
While insulting Chris and Meg's intelligence in "Baby Stewie", Brian refers to them as a couple of Bozos. When Stewie questions if he means Bozo the Clown or 'Bozo the Tax Accountant', he sets up a cutaway gag of Bozo naming various work deductions for a client's sex advice column using sound effects.