Originally Posted by Eric F

This ^^^

As others have also noted, it could be a combination of things, including bent chainring or cog teeth, but the fact that it's related to going over a bump makes chain tension a most likely culprit. On a beach cruiser type bike, adjusting chain tension would require loosening the nuts that hold the rear wheel in the frame, sliding the wheel back, and re-tightening the nuts. There is a balance between too loose and too tight for chain tension. Too tight will make pedaling more difficult. For someone with experience working on bikes, this is pretty elementary. For someone without experience, it might take some trial and error to get it right. Also, make sure the wheel stays centered in the frame.