In large pot, heat grease on high. Add kernels and place lid on pot. Shake pot back and forth to keep kernels popping.
When popping slows, remove from heat. Garnish with cheddar cheese and fresh bacon bits if desired.
Notes
Use a large, heavy-bottomed pot. A heavy bottomed pot will distribute heat more evenly so that hot spots aren't created which can burn the popcorn. Use a large pot so that the popcorn doesn't overflow.
Before adding all of the kernels to the hot bacon grease, just add a couple first so you can test the temperature. Once those pop, your oil is hot enough and you can add the remaining kernels.
Shake the popcorn as you are cooking it so that all of the kenels cook easily and don't burn.
Tip the saucepan lid occasionally to let the steam escape so that you don't have soggy popcorn.