Speaking of not knowing what to expect: your methods not only don't know what arguments they're going to get ahead of time but occasionally, they don't even know how many arguments there will be.
Let's say you have a method, friend, that puts the argument it receives from the user. It might look something like this:
def friend(name):
puts "My friend is " + name + "."
end
This is great for just one friend, but what if you want to print out the all of the user's friends, without knowing how many friend names the user will put in ahead of time?
The solution: splat arguments. Splat arguments are arguments preceded by a *, which tells the program that the method can receive one or more arguments.
Run the code. Feel free to play around and call what_up on as many friends as you like!