Instead of constantly pushing your glasses back onto your face like a 90s movie nerd, weblog Tested recommends wrapping the ends in a bit of heat shrink to keep them from slipping.
While it's definitely one of the more involved ways to fix the sliding glasses problem, it's going to look and feel a lot better than, say, slapping some duct tape on the back. All you need is a bit of heat shrink tubing. You'll also need a source of heat, like a heat gun, but if you don't have a heat gun, you can always try something else.
They claim a hairdryer probably won't produce enough heat, but it's worth a shot and a lighter might work if you're very careful, like the 16:45 mark in this video. Whatever you do, just be very careful, and familiarise yourself with the safety of your chosen method. Check out the video for more info.