should we be offended?

It’s a much vulgar version of the much older “je m’en tamponne le coquillard”, the literal translation being “I’m patting my privates with it” meaning “I don’t care.”

There’s a famous song “Les nuits d’une demoiselle” by Colette Renard with lyrics in periphrases all describing sexual self-satisfaction using French language twists and vocabulary. A real gem!