Fun video.
You should pick up what is known as a tear stick. It is a wax stick in a lipstick mechanism, that contains menthol and camphor. You rub it under the eyes, on the orbital bone, and it causes you to produce real tears. These range from $5-10 including shipping.
The more expensive, but faster and more effective option is the tear producer. The tear producer is filled with menthol crystals. The device has a little fan in it that blows the menthol fumes near the actor's eye to produce real tears. Professional use only. You can really hurt yourself or others with this. These run around $40 + shipping and refills are around $10.
I've used both. The Tear Producer is by far the most powerful and fastest, but some actors cannot handle it. First time I saw or used one they had used it on an actress in a scene, but it was too much for her and she was crying too much. SO much so they had to break until she could stop crying. So then i tried it. It made my eyes water really, really, fast and really, really, hard. If you want just a single tear, this is not the correct option.
A cheapo option is to use a vapor rub (like Vicks) on the lower eye lid. Be Very careful not to get it in the eye. It takes a moment for it to kick in, and it is shiny on the surface of the skin so it will not work in all situations. One benefit of the vapor rub is that can be applied to a tissue and the actor can apply it mid scene.
As always test ahead of time and watch for allergies or adverse reactions to any chemical used on or near a person.
