I'll agree that the ivory parchment is a wonderful idea -- it adds a lot of class and dignity to sucking cock through a cum-stained gloryhole. I'll respectfully have to submit my opposition to a fancy script, however: could easily frighten a guy into thinking he's received a wedding invitation. I'd stick with a standard 10 pt. arial font -- but that's just me.
No, seriously... I like the idea of passing a note through the hole. Reminds me of "the good old days." Though I've never passed a note myself, I was handed quite a few of them in my youth. This was AGES ago, however -- and I was always kind of surprised at the audacity of the guys who passed the notes since the venue was a public restroom in a department store (discovered accidentally by me during my first year of high school when I would change busses in the business district of downtown). In an ABS or a situation where the guy has already stuck his dick in the hole or has a visible erection, probably there is little concern that a written statement of testicular intention would be inadvertently handed to a cop, right?
I'd personally experience a warm wave of nostalgia if I were handed a note through a hole today. Alas, it's not about to happen anytime soon, I don't think.