"... an accusation that the Tutshill Tornados were winning the Quidditch League by a combination of blackmail, illegal broom-tampering and torture; an interview with a wizard who claimed to have flown to the moon on a Cleansweep Six and brought back a bag of moon frogs to prove it..."
-- Harry reading The Quibbler, OP10
Someone interviewed by The Quibbler claimed to have brought back a bag of moon frogs to prove his claim that he had flown to the moon on a Cleansweep 6 (OP10).
Harry reads The Quibbler, tired of the article on Cornelius Fudge, so he reads the account about moon frogs a few pages later (OP10).
"Luna" is the Latin name for moon, so the Quibbler story about someone flying to the moon on a broom and bringing back watery creatures such as frogs fits perfectly.