If they're not cleaned every few days, houses will turn black and begin emitting a high-pitched scream that makes dogs pregnant. Prevent a neighborhood outbreak of puppies with today's Groupon: for $49, you get $100 worth of pressure-washing services from Under Pressure SC. Today's Groupon is valid for houses in Charleston, Berkley, and Dorchester counties.

Under Pressure SC's licensed technicians obliterate exterior dirt, mold, and detritus with supercharged cleansing jets. The four-step pressure-cleaning process commences with a surface soak, as showers rinse away loosely stuck grime, errant leaves, or posters of the house's favorite teen heartthrobs. Chemical elixirs then penetrate into encrusted gunk encampments, softening deposits in advance of a vigorous brush bath.

After stubborn blotches have been suitably dislodged, technicians return home expanses to gleaming luster with an all-over aqueous blast from a commercial pressure washer. Bust barbecue remnants off of begrimed patios (starting at $49 for 400 sq. ft. or less), clear car droppings from sooty driveways ($69 for 20 yds. or less), or hide the evidence of failed graffiti-tag designs with a freshly erased home exterior (starting at $139 for 1,500 sq. ft. or less).