Back in my gay sportbike days, I used a crayon in the stampings.
I smushed the crayon into the letters scraped off the excess with my thumbnail and let the sun do the rest.
I don't recommend this, but I bet YouTube had a tutorial or two.
What I liked about it is when I became ungay, I used a toothpick to scrape it out.
If you were any kind of "friend", you'd taste test for them...lolDo oil base crayons taste different than regular crayons?
Asking for a Marine friend..