Can occur when your board suddenly gets traction in the middle of a slide or, in extreme cases, a very sharp turn. What happens is that the wheels refuse to let go (which you need to be able to slide). This simply causes the board to flip. If you do a heelside, it usually isn't as unpleasant as it is when you do a toeside. In a toeside, your back is to the slope and if the board flips, you fly off and have to do an acrobatic turn in the air to avoid getting hurt. Does that sound nasty? It is. Highside is not something you want to happen.
To avoid highside, you need to remember not to ride with wheels that are too grippy and to hang your weight out on the board when you slide. Another solution can be to let your feet hang out a little outside the board so that you push it in front of you in the slide itself.
