This is a concept I've tried a few times to use as a basis for a NSFW Bonus strip on Patreon, but I've never pulled the trigger. Mainly because I always came back to the feeling that it works better without a cut away to naughty stuff. So instead of having the characters in a drug store and John getting hot and bothered, I used it as a gag in the answering of a question... still works pretty well I think. I've used it before, but I still laugh at the idea of using subtitles in a comic strip... it's just so unnecessary for the type of media that I find it hilarious.