2. Cranky Doodle Donkey arrives in town and tries to avoid making contact with any of the ponies. Pinkie finds him/her and welcomes him/her with open arms, but Cranky turns down Pinkie's offer of lifelong friendship and storms off.
3. Pinkie becomes confused and paranoid, convinced that this is not right since no one ever refuses to be friends with her.
4. Pinkie goes to extreme lengths to make Cranky turn. Eventually Cranky decides to humour her and goes to one of Pinkie's parties.
5. The episode ends with Pinkie learning that it is OK if not everypony wants to be friends, after all she can only have so many friends at one time. Cranky then takes a shine to Pinkie Pie's rational decision and agrees to Pinkie's request for life long friendship.
I don't know if Cranky will be a male donkey, but I sincerely hope it's Weird Al doing the voice!