I need help I suck at romance SOS!

I'm deeply in love with my boyfriend, my first for everything, and I want to get promise rings. He likes the idea but is reluctant due to a past relationship (I know usually that's a sign but if you knew you'd understand). Anyways I want to give his to him before I go out of town for a couple weeks. But how on earth?! I need it to be perfect! ( we are very lighthearted couple so something funny yet sweet would be perfect ) thanks!