You might want to think twice before drinking from your office coffee mug. Experts say up to 90-percent of them are loaded with germs. They say kitchen sponges that are rarely changed are the source. The study was first published in the journal "Dairy, Food and Environmental Sanitation" out of New York's Cornell University. Hundreds of bacterial strains have been identified, including E. coli. Researchers suggest taking your mug home each night and putting it through your dishwasher.