Dime is a slang term for something considered attractive or desirable, particularly in a physical way. It's often used to describe someone who is considered very attractive.
Here's how it's used:
* "That new guy in our class is a total dime."
* "She's a real dime, I've got a crush on her."
However, "dime" doesn't directly refer to an "I" sound. The slang use of "dime" developed over time and has no direct connection to the letter "I".