Of all the slack that Millennials take, this one might be the most merited. According to a new study, young people in this age range are terrible tippers. Credit cards.com surveyed 1,000 people and found that 10 percent of adults 18-37 routinely don’t leave any tip on their restaurant checks. And when Millennials do tip, it’s not nearly on the same level as other groups. At restaurants, nearly a third of tipping Millennials chose to leave less than a 15 percent. When presented with preselected options on a tablet (usually at a coffee shop or after taking an Uber), one in six Millennials choose the lowest amount, while one in five choose to leave nothing. Older age groups gave more generous tips in every situation. The study also found that across all age groups women are better tippers than men — going against the outdated thinking that men, as a whole, leave better tips. The median…