To play as the Comedian, and thus unlocking this achievement, you'll need to earn a kill using the banana peel. You can also kill yourself on it to earn this achievement.
First, you'll need to get yourself a banana peel which will be added to your inventory once you've eaten a banana. Banana's can be found in trash cans or fridges, or use the Gorilla as your starting character (if you have him unlocked) as he always starts with one in his inventory.
Banana peels, when slipped on, will deal 5hp of damage which can be a little tricky. You can either:
- Take an enemy's health bar down to 5hp and hope that they're still chasing you to unleash your peel before them (more often than not, enemies will flee when they're low on health) or;
- Let an enemy beat you down to 5hp and then use the banana peel on yourself, which is arguably the easier option.