Farmer here,

The trick is to buy a linden tree scented candle that naturally smells like putrid cum to cover the smell of actual putrid cum.

You can buy one here:

https://us.amazon.com/Yankee-Candle-Large-LINDEN-TREE/dp/B01N3OLHLJ

Now that you have your cum candle, it's time to make some fake cum for your parents.

What you’ll want to do is take about a 1/4 cup of water and mix it with your corn starch to allow it to slightly dissolve. Take the remaining 3/4 cup of water and put it on simmer on the stovetop in a pan. Combine the stirred cornstarch and water into the pan, whisking them together. It will quickly mix together and become very thick. Once it is, remove it from the burner and allow it to cool to room temperature. If you wish to speed up the process, you can create an ice bath to place the pan on or stick it in a fridge to cool down. You’ll want to do this prior to adding the egg white, because if it is still hot you risk cooking the egg instead of incorporating it. Take the egg white and yogurt and mix them with the cornstarch and water mixture. During this time, you can add a pinch of salt to get it to the desired taste. Set your mixture aside until ready to use!

This will keep for about a day or so, depending on how quickly you can stick it in the fridge. Do not leave it out, since the egg whites and yogurt can easily spoil in room temperature.

Once your fake cum is done you should spill the whole bucket on your carpet and lit about 10 to 12 linden tree cum scented candles.

Once your parents arrive they will be greeted by a puddle of smelly cum in the middle of the room.