It's really hard when they don't have any interests or hobbies that you can go off of.
What about colors? Or style? I had a girl that I just did a 17th birthday cake for and all she said was, "I like patterns and bright colors." I had to draw some more out of her. Patterns? Do you like polka dots, stripes, diamonds, hearts, flowers, etc? And I got her to name specific colors like turquoise, lime green, orange, hot pink, etc and I just went from there.
The "package" with a "bow" is my standby idea for guy cakes. You can use guy colors like black and white, sage green and dark green, yellow and green, etc.
You can make it as simple or as fancy as you want, use fondant or buttercream, etc. You can use any shape of pan, any configuration of "gifts" for tiered cakes. Here are examples from Wilton and an example of a sheet cake.
Sure! I've done two different ones. The first one posted was actually done by default...I was trying to do a 3D red solo cup and it kept falling over on me. :( Luckily, it was just for my brother-in-law, I really had the freedom to do whatever I wanted. The cup on top of the cake was actually a real cup filled with cake and frosting that I just stuck right in the round cake.
My second one I figured out how to make the 3D one work...definitely my favorite of the two.