It starts singing about big bird and snuffy. I feed the mimic some caltrops.

 It gives you a glare. I then feed it caltrops.

It spits out ball bearings.

I feed the mimic a dragon head.

It breathes fire at you, incinerating you instantly.

I feed the mimic a pair of old boots.

It's mannequin feet then grow boots and tap dance. I feed the mimic a nearby person.

Okay, you are currently standing next to a Mr. Potato Head, so you feed it that. It eats it, and spits up Andy.

I feed the mimic Smaug. 

The mimic hasn’t eaten something that big, so it starts gnawing at it but by but. It spits out (after it is finished) a massive Black Arrow. Make a Dex save with disadvantage, LeviRocks. If less than 15, take 527829 necrotic damage

I feed the mimic a brownie

Dex Save:

23500

Quote from LeviRocks >>

Dex Save:

23498

Obviously, you've been eated by the Mimic...............

I feed the Mimic a ton of salt after you've been eated.

The mimic chokes down the salt, spitting out salt cookies.

I feed the mimic my favorite teddy bear :(

I feed the mimic a pair of dwarf legs.

The mimic gobbles up the teddy bear and the dwarf legs and spits out a teddy bear with muscular dwarf arms and legs

I feed the mimic a sabaton album

the mimic spits out a record player

I feed the mimic another mimic

It spit out some pieces from the mics he've eaten before.

I feed the Mimic a ton of recently boiled Wax.

It gobbles down the wax super fast and immediately spits out a wax figure of itself looking REALLY cute...

I feed the mimic 100 packs of gummy bears

After thanking you for the sweet treat, it spits out a USB flash drive with the gummy bear song on it.

I feed the mimic the complete dvd run of south park.

the mimic spits the  DVDs out

I feed the mimic a baby dragon and a cupcake

The mimic spits out the rabbit in your  profile pic. I feed the mimic a bomb.

the mimic spits out the bomb just before it goes BOOM!!!  

I feed the mimic a mimic and I didn't feed the mimic the bunny on my profile pic!!!!!!!!!!!!!

The mimic refuses to eat the other mimic, as it has with the ones before. Instead, it takes the mimic with its prosthetic arms and throws it at you. 

I feed the mimic a cake from my bakery that says in icing, “The cake isn’t a lie”.