An interesting way to remind yourself to do reality checks.
write "Are you dreaming?" down on the side your index finger. That way whenever you are looking at your hand, or even just something in/near your hand you'll remember to do a reality check. Then you look at your watch (or the nearest clock) and do a reality check.
It also looks pretty cool when you make a fist, because it says "are you dreaming?" and it's wrapped around in a spiral.
What other methods do people use to remind them to do reality checks throughout the day?