I think he keeps it in a pocket, or by his side. But it is Physically impossible, besides he is a platypus.
Perry the Platypus's hat is brown.
It is described as a "1940's fedora".
Perry the Platypus was created in 2007.
In Phineas and Ferb, Perry the platypus wears a hat. The reason he wears this hat is to supposing hid his identity. As all the animal agents, he wears a small brown hat to show proof that he is an agent. Like a small badge. PNF-FAN!
Perry, perry the platypus, or agent P
Perry the Platypus, the pet platypus / secret agent Perry from the Disney show, Phineas and Ferb.
Google "perry the platypus tumblr theme".
Male, they show Perry in love with a female platypus in an episode
A Platypus.
His beak is orange or tangerineAnd Perry is not an accurate example of a Platypus.
Ask Perry the Platypus
CIA Agent Perry is a platypus, a pet of Phineas, Ferb, and Candance. He is also an undercover secret angent, using a hat to switch to and from his two identities. With the brown hat on his blue head, he is a secret angent, foiling gis arch enemy Doofenshmirts's seemingly "evil" plans. With no hat, he is Perry, an ordinary, inactive platpus.