Get past the second checkpoint in level 8. Collect the flower on the right to set yourself on fire. Then, jump in the pit with the cupcakes. Because you are on fire, you will kill every enemy upon contact. Keep moving to avoid dying. When the cupcakes are killed, they will respawn very fast from the presents. Keep running in the pit. Avoid the venom spitting plant on the left. The venom will extinguish the fire. Note: You can avoid the spitting plant by jumping in, running halfway through before turning around. Then, jump out, turn around, and repeat the process. Additionally, you may have to die by remaining still while burning to earn "Roller Toaster".
Easy "Surgical Strike" achievement
Get to just past the first checkpoint in level 8. As soon as you walk over the springboards, bouncing hearts will spawn from the presents. Wait until the bouncing heart almost hits you before jumping. If you jump too soon, you will land before the heart hits you and die.