I'd love to see former housemates return...
 

...for tasks.

Suck My Big One
Angie leads housemates in a lollipop sucking contest, each one with a key inside. The first person to reach their key receives a special prize / immunity / something.

David's Dead
David Gest lies with his eyes closed in a casket covered in sweets and the housemates have to sneak up and take some without him noticing.

I Clean Everyone's **** Up
Megan leads the housemates into the task room which has been transformed into a messy flat. They all have to clean up the flat and find a series of prizes, like a cross between Fun House and Finders Keepers.

I would watch this for some strange reason.

Honestly this sound dreadful

they have already done this