Here's how: Your skin has oily and watery layers (if you remember your middle school chemistry, oil and water don't mix), which makes it good at protecting you from outside molecules. However, garlic contains a molecule called Allicin, which has properties of both water and oil. Because of this, it can permeate the skin in your feet and travel through your blood all the way to your mouth and nose. You'll swear you can taste garlic and that the room has a strong garlicky odor.