Googled it. I found some vague references to it having happened, or having been stopped in the act, but not like a news report. The more prevalent an idea is without having any actual evidence, the less I trust it.

Seems like a real thing:

https://www.sun-sentinel.com/news/crime/fl-ne-fugitive-roy-k...

Someone was mailing drugs into federal prisons, disguising papers soaked in MDMA (commonly known as ecstasy), fentanyl, synthetic marijuana and Suboxone, an opioid dependence treatment, as confidential legal communication in order to sneak them past guards.

https://www.npr.org/2021/07/15/1015447281/overdose-deaths-st...

Friends and family can tuck strips of paper soaked with drugs into mail or books, and if they get past the mail room, people in prison can eat them, or roll them up and smoke them.

https://bangordailynews.com/2020/06/25/news/state/3-maine-wo...

Three Maine women have been accused of being associates to a New York City street gang called the Bullies that allegedly used vehicles with hidden compartments and comic book pages soaked in narcotics as part of their multi-state distribution of cocaine, heroin, guns and money between Maine and New York for 3 ½ years.

Found on first page of:

https://www.google.com/search?q=heroin+soaked+book

It's real. It's mostly roach spray though: https://lumierehealingcenters.com/2018/07/12/drug-alert-smok...

I just got out of jail. This stuff is EVERYWHERE.

> The stories of paper goods (including mail) being soaked is prevalent.

I didn't believe it when it was LSD getting to kids : https://en.wikipedia.org/wiki/Blue_star_tattoo_legend and I don't believe it now.

There is no financial reward in giving LSD to kids so that’s obviously fake.

There is an enormous financial incentive to smuggle drugs into prisons by any means, and soaking drugs in paper has been done all over the place. Here are 3 cases:

https://www.justice.gov/usao-ndoh/pr/eleven-people-indicted-...

https://www.justice.gov/usao-wdpa/pr/multi-state-drug-smuggl...

https://www.justice.gov/usao-wdpa/pr/two-sci-inmates-two-all...

LSD gets to kids in e.g. cake sprinkles. There was an incident with students hallucinating at my junior high (a long time ago), and I overheard some of the responsible kids talking about it later on.

Excellent reason to ban all books in prisons.