how come when i pour gas into my lawnmower the gas drips out under the cap where i screwed it on?

like its a blitz regualr one gallon gas can and i pull the tubing out and when i tilt it to pour the gas out it comes out the spout but other excess gas from the can spills everywhere what can i do about this? i made sure ti was screwed on safely and all of that nonsense! but it causes so much havoc! any good answers are neccesary! thanks in advance!