Lather

[Sarah]

To spread over with lather; as, to lather the face.

[Sarah]

The lather effect is a drinking term that stems from a shampoo analogy. When you shampoo your hair the first time it takes a large palmful of shampoo to create a nice lather. However, after a quick rinse it merely takes a little drop to gain a full healthy lather. Similarly, if you drink hard the night before, it only takes a very small amount of booze to get you ripped the next morning.

[Sarah]

When soap is applied to the body and spread around during a shower

[Jessica]

A frothy white mass of bubbles produced by soap, washing powder, etc. when mixed with water.