Cover large portion of counter with wax or parchment paper.
Pop the popcorn and put in a large bowl. If using bagged popcorn, pick out the kernels.
In a medium bowl, melt the chocolate chips in the microwave in 30 second increments. Stir chocolate until smooth, add cake batter and oil and mix well.
Pour chocolate over popcorn and mix well with rubber spatula, being careful not to break popcorn.
Add the crushed Oreos and M&Ms and mix well.
Dump popcorn on prepared counter space and spread evenly. Allow to cool for 10 minutes.
Keep in an air tight container for up to 5 days.