The hokey-pokey is a classic dance that's often done with children. The dance is so easy to learn that you don't even need to know anything about it before you begin; the leader will take care of it by calling out what you're supposed to do, i.e., "you put your left hand in, you put your left hand out, you put your left hand in, and you shake it all about." This dance works well for children who are still learning their right from their left.
The Macarena was made legendary by the song in the mid-'90s of the same name by Los del Río. It became an instant classic, danced and played everywhere from school dances to weddings. The dance requires a little bit of instruction beforehand, but it's quite simple to get the hang of and you may be able to pick it up just watching others. You'll stand in a straight line and extend and rescind your arms in time to the music in a pre-set pattern before jumping to the left.
The waltz has many variations and can get pretty fancy, but the groundwork for it is very simple. The waltz itself is rooted in the "box step," meaning you'll step into a pattern of a box. Since this is a partner dance, the couple will face one another and the man will begin with his right foot forward while the woman begins with her right foot backward. The couple will simply continue the box-step pattern.
The chicken dance started out as a fad dance in the '50s, but it's still often done today. Danced to accordion music of the same name, dancers stand in a circle and place their hands at shoulder level. They will open and close their hands like chicken beaks three times, flap their arms like chicken wings three times, shake their hips and then clap in time to the music. When the music changes, they'll hook arms with someone next to them and skip in a circle.