I know that people have done it, but that's not really the point of Bitcoin and the cost per byte is higher with Bitcoin than altcoins. You could do it to cheaper altcoins or forks but then you run into the issue on them being around long-term. (I believe someone put Windows XP into the bsv blockchain?, And eth has an asic drawing in it's chain?)
Think 5000 years from now. Altcoins probably won't survive that long.
So... you want to write blockchain spam, ie a written message to the blockchain?
Because buying a coffee with bitcoin isn't spam /s