This cool trick, done in the "Lower Corridors" during the part where you're trying to get your egg back from Mr.Skeltal isn't all that hard. You need to position yourself in a way so that the Haunted Chair hits you past the trigger for the Spooky Arm, allowing you to save a few seconds. Video for reference:

Another trick you can do that's similar to the one above, on "Kitchen" during Chapter 3 when it's taken over by Medusas, you can trigger the first second or two of the scare animation for the Medusa nearby the exit door, but skip the rest. This strat seems to have no use though currently other than making you feel like a complete badass, or saving you from losing a few extra seconds in your run if you trigger the Medusa. Just hit the trigger for transitioning to the next level right as the Medusa detects you. Video here: