Sorry. I probably should have linked happy and sexy. I was saying that the "happy" component fit well with the topic. Sexy was just an added bonus.

To summarize:

If you take a number, sum the squares of its digits to make a new number, then do the same with the next number and it eventually reaches one through that process, it is a "happy" number. "Happy prime" just refers to those prime numbers which are happy.

Demonstration: 3^2+1^2=10 and 1^2+0^2=1

a sexy prime differs from another prime by 6 (in this case; 37).