My daughter and I have a joke between us when she becomes impatient. If she keeps asking for multiple things at the dinner table and believes that she isn't getting what she wants quick enough, I say "Ah, mommy only has 5 hands or I'd be quicker". Then, she either smiles or says "You don't have 5 hands, you only have 2 hands". I then respond with "Oh, that's why I am so slow!". Even though I am being silly about this to her, it reminds her to be patient and just wait.
Children can't properly learn to take turns with peers and share toys if they haven't learned to be patient. Some ideas on helping toddlers and young children to wait is to not jump for every request they have. If you are busy, take your ole' sweet time and then respond to their wants.....unless the situation is a dangerous one which calls for a speedy response! Also, give them choices to slow down things. For example if your little one is grunting for a drink, you can show him (or her) 2 cups and let him make a choice. This just added at least 15 seconds to the time that he would have initially got the drink. Modeling patience is important as well. When you are at a store with your child, they are watching your responses to the cashier and other staff. Even if you want to complain, hold it in, because it is hard to teach patience if you yourself don't display it.
My 14 month old son seems to like to squeal while in his highchair to express his impatience; not a fun behavior. I do not respond to his request for food until he has quieted down. I give him a small amount of food as well so he has to communicate when he wants more by using sign language or making sounds. He says "nana" for all foods even though it was initially for bananas.
Other ideas to teach patience include playing games in which the child has to wait and then respond. An example includes rolling a ball back and forth to each other, or build a building with blocks while taking turns in who adds the next block. Most importantly, remember to be patient while teaching patience!