(After a quick look at your site) I suspect your students will not get
very excited about a program whose sole purpose is to get you to click on
a "Hello World" button 10 times, counting the number of clicks made. But
then again, I still don't know anything about your student's interests.
I'm assuming "20 hours of exposure" is something along the lines of "heard
the term 'compiler', but hasn't actually used one yet."

   What's the goal here? Some example answers:

   (a) These are students who are already enthusiastic about programming,
and so you want to get right into teaching programming with Java without
killing that enthusiasm with otherwise boring theoretical stuff.

   (b) These students are "into" computers, as shown by their electing to
come here, but they've no particular interest in programming. You want to
introduce them to the wonderful world of programming.

   (c) These students have no idea what to expect, and you want to give
them a taste of what computer science (contrast with programming itself)
is all about.

   etc.

   If "entertainment" truly is the only motivation, and it has to somehow
involve Java, just let them play around with
http://bytonic.de/html/jake2.html all day. Assuming you want the students
to actually look at the Java code, it's not clear to me whether you expect
the code or the program to be entertaining. If the former, I'm not sure
how entertaining Java code can be unless the viewer actually knows a
decent amount of Java.

   - Oliver