Change one letter.

[Slime]

Perk.

 

[Mottie]

Park

 

[Slime]

Hark.

 

[Mottie]

Hard

 

[Slime]

Harm.

 

[Mottie]

Farm

 

[Slime]

Fart.

 

[Mottie]

Tart

 

[Slime]

Tort.

 

[Mottie]

Fort

 

[Slime]

Fart.

 

[Mottie]

Fart.

You did it again………

 

[Slime]

You did it again………

Doh!
Let's have another go, the word to change was Fort, so I'm going;

Fork.

 

[Mottie]

Cork

 

[RandomGrinch]

Dork.