Unintentional innuendo in middle school

My middle school boy has run into a few instances recently in which he did something that seemed to him harmless and that his classmates interpreted sexually. In one case a girl was offended and reported him to a teacher as making lewd jokes to her (which he totally was not). In another case all his classmates were laughing at him and he didn't know why. He is more innocent and sheltered than most of his classmates, it would seem, although he does know the basic facts of life. He's still early in his puberty development, too, and not really interested in girls yet. I don't want to try to explain all kinds of sexual innuendo to him. He's definitely not ready for that. I also don't want him to keep being made fun of or falsely accused. How can I help him navigate this?