lather something up
to apply thick soapsuds to something, such as part of the body or all of it. He lathered his face up in preparation for shaving. He lathered up his face.
1. [for a horse] to develop a foam of sweat from working very hard. The horses lathered up heavily during the race. Don't let your horse lather up!
2. [for soap] to develop thick suds when rubbed in water. This soap won't lather up, even when I rub it hard. When the soap lathers up, spread the lather on your face and rub.
3. and lather oneself up [for one] to apply soap lather to one's body. He will spend a few minutes lathering himself up before he rinses. He lathered up and then shaved.
1. To cover some surface with lather or foam: He lathered up his chin and shaved the stubble. She lathered her hair up with the new shampoo.
2. To produce or become filled or covered with lather or foam: This shaving cream lathers up as soon as you put it on your skin.