Tears are secretions to clean and lubricate the eyes. And there is a precorneal film covering the eye. We usually cannot feel its existence.
As we open and close eyes, the tear film can be inhaled into nasolacrimal duct. Only when we laugh, the pressure in the nasolacrimal duct increases, the tears cannot flow into. At the same time, the eyelids close. The tears cannot flow in, but being squeezing continuously, at the end, the tears come out.
Speaking for myself, you rarely have the same experience with you. It seems that tearing while laughing is strange, don't you think so? But you shouldn't worry about it too much, because you gotta bear in mind that different people have different body types right? So, shedding tears while laughing , if the tears cannot fill a pool, is normal. But if you have several other uncomfortable feelings in the mean time, then it is possible that you really have something wrong with your eyes. Anyway, may you good health and perfect vision.