I found python to be the easiest language to pick up, with a naturally gradual transition from command line to a simple IDE (Idle), and some very accessible libraries for further amusement (pygame). It's fun but I am glad that it's not the only language I know!
If you think they might stick with it, it has been stated that it's better to learn a more strict language initially, to enforce better understanding of underlying factors, and to avoid acquiring some bad habits. Most often one sees suggestions to learn the relatively abstract languages C++ or Java, as opposed to the more fundamental,"low-level" C.
The problem I see with Python and most other languages on Ubuntu is that it's hard to make graphics. ("cool pictures")
Actually I would suggest something even more basic, like HTML. This primarily for 2 reasons. 1) It is simple to learn and implement, plus it is very easy to see the results of that coding. 2) This will give him an idea if programming is still a good fit for him. I would hate for him to take up some other language and get frustrated with it and then give up on the whole idea.
I can't really agree with this. There's nothing wrong with learning HTML, but it's markup, not code. Learning HTML teaches you nothing about variables and storage, declarations and definitions, branching and control flow, procedural and object decomposition, etc. In short, it's not programming.