In case you didn't know it, the optimal tooth brushing time is two minutes with enough pressure to get those bristles int
If you don't brush for at least this long, you won't get rid of all that bacteria-packed plaque.
But if you don't want to set a timer every time you pick up your toothbrush, do this:
While you scrub, hum along to the Beatles' song "Yellow Submarine." But skip the last chorus. It'll time out to exactly two minutes.
And if you can't remember the tune to that one, try humming the song "My Favorite Things" from The Sound of Music. That'll work too. If you don't know that one either, you're out of luck. Go buy a timer.