Well first you should get an [anal speculum)[https://www.amazon.com/Best-Surgical-Pratt-Rectal-Speculums/dp/B00IDCJLWU) to preserve the integrity of your ass toast.
Assuming your ass toast really is the best kind, you may also want to get some premium preserves that go well with toast, and can double as a lubricant. I recommend St.Dalfour brand, available at your nearby Whole Foods or hoity toity market.
Then with your tasty preserves lubed anal speculum in place, gently apply the eggplant by jamming it in there.