It's embarrassing enough for an MLB player who tests positive for a banned substance.

Now imagine the player trying to explain to MLB officials that the positive test resulted because he had taken some sexual-enhancement pills, the type commonly sold in gas stations.

That's happened to at least two players this year, according to ESPN. The report noted the use of such pills among players is so "prevalent," MLB sent out a memo Monday warning of the dangers of such supplements.

The letter, which was sent to all MLB players, as well as minor league players and the players union, noted that "these products are often contaminated with prohibited and unsafe ingredients" and that players can be disciplined even if they inadvertently ingest a banned substance.

"Sexual or male enhancement products present a very real risk for drug-tested players," the memo continued, "and the high likelihood for contamination or unidentified ingredients in these products underscores the importance of consuming only those products that are NSF Certified for Sport."

The MLB memo noted that players who "suffer from erectile dysfunction or other legitimate issues related to sexual performance" contact a physician to get prescription medication to treat the condition.

As you might expect, ESPN reporter Jeff Passan's tweet on the MLB memo about the use of "gas-station sexual-enhancement pills" prompted plenty of middle-school-level jokes and double entendres.

Example: "If your baseball game lasts longer than 4 hours, call your physician immediately."