Lets see... Dy2 =Dy1 +Voy(deltaT)+1/2Ay(deltaT)^2
Lets say you're laying on your bed which is situated 4 feet above the floor (1.22 m), and your ceiling is 12 feet from the floor (3.66 m), so you're trying to cover roughy 2.44 meters. Acceleration is always 9.8 m/s^2 downwards in the vertical component due to the gravity of the earth. How about we give a fair estimate of 1.5 seconds for how long (if even possible) your cum would have to be travelling in order to travel from your cock to the ceiling.
3.66 m = 1.22m + Voy(1.5 s) + 1/2(-9.8m/s^2)(1.5)^2
2.44 m = Voy(1.5s) + (-11.025 m)
13.465 m/(1.5)s = Voy(1.5s)/(1.5s)
Voy = 8.98 m/s
Theoretically, your cum has to be coming out of your cock at 8.98 m/s for it to be able to touch the ceiling. Just for some scope, this means your dick is shooting at a little over 20 miles per hour.
So, I'm calling bullshit on anyone who says they can hit the ceiling if their conditions are anything similar to this. I'm not ruling out a bunk/lofted bed or a
very low ceiling, but anyone who says they shoot from a king size bed to a fairly average ceiling height is on a physics level a very impressive specimen (if real)
p.s.: any other engineers in here can correct me on my calculations if they're wrong. It's been a while since physics and also I've got my calculator in my left hand and my dick in my right