Didn't feel like spending money on a watering can. Didn't want to just dump water on my plants and risk damaging them. So I did this:
Step 1: What You Need
1) A plastic bottle with a wide opening and a lid. I used a Simply Lemonade bottle, but any sturdy plastic bottle will work.
2) A drill with a 1/8 inch bit. (or some other way to poke holes in the plastic, but this is the easiest when using more durable plastic)
Step 2: Drill Holes in the Lid
Use a clamp or something to hold the lid steady. I didn't and when the drill caught the plastic, it just started spinning it around. Drill evenly spaced holes in the lid.
Step 3: Drill an Air Hole in the Bottle
Up toward the top of the bottle, drill another hole or two to allow air into the bottle as you pour, otherwise the water will barely dribble out. Be careful with this part as the bottle can be slippery and the drill will slide off instead of going through the bottle. Do not use your feet to hold the bottle steady.
Step 4: Use It
Fill the bottle with water, screw on the lid, pour over plants.