Want another reason why you shouldn't smoke (besides the fact that it's bad for you and smells icky)? It makes you look old, and not in the "I can pass for 21" way. Just ask Mary-Kate Olsen.

Word on the set of Showtime's Weeds is that MK, who's just recently signed on for some eppies of the show, has to spend some QT in the make-up chair to cover up her blemishes and dark circles around her eyes. (Proactiv isn't the solution here.) And according to TMZ, the show's crewmembers were overheard gossiping about how old the 20-year-old looks in person. Also adding to MK's haggard look is all the coffee she drinks. We guess MK and Ashley's tutor on the set of Full House didn't remember to cover everything you're supposed to learn in health class...

Thank god for post-production cosmetic fixes!