21st Birthday Party

My son's birthday is March 21 and his girlfriend's is March 20. They will both be turning 21 this year. My parents and great grandma are coming three hours away for the party. I want to make a special cake for them together because it is an important birthday. Any suggestions? I asked my son today what they liked to do together he said oh just sit around and watch t.v. cause we don't see each other that much or have time for anything else. Then I asked him what Kelsey liked, flowers, butterflies, favorite color, etc..... He said I don't know mom. GEEZ!!!!! Anyway, little info on the two: He works at the casket company, likes golf, music, and skateboarding. She works at McDonalds, cosmetology school, has a tattoo of a butterfly on her foot, and a very sweet girl. I was going to doing a golf cake made out of cupcakes and then put flowers and butterfly cupcakes around as the border. Wished I could think of how to combine a casket and cosmetology. Here is a pic of the two!