What are some really easy,fun things to do with STRING?

I have lots of colors snd know how to make 3 string braids...is there a VIDEO explaining how to make 4 string braids? What are sone other easy things? No weaving/crocheting...does anyone know how to make the thing where you use two pieces of yarn and tape it (so it's easier to work with) and make use one string to make a loop and then use the other string and do sumthin so that it makes little knots?(what's it called) if you have any other ideas PLEASE tell me!!:) thx for you're help..that is if u dud something;). Bye.