Whack-___

• Whac-__: arcade game
• Soap-producing plant
• Root used as a soap substitute
• Root used as a cleanser in Mexico
• "...mountain out of --- hill"
• Blind as ___
• Soap substitute
• Soap plant
• Agave root

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Amole \A*mo"le\, n. [Mex.] (Bot.) Any detergent plant, or the part of it used as a detergent, as the roots of Agave Americana , Chlorogalum pomeridianum , etc. [Sp. Amer. & Mex.]