noun, feminine/mas.tyʁ.ba.sjɔ̃ ɛ̃.tɛ.lɛk.tɥɛl/plural: masturbations intellectuelles
intellectual masturbation (showing off one's own intelligence or knowledge in a way which distracts from helpful or meaningful discussion)
Synonyms: branlette intellectuelle
Literally, “intellectual masturbation”.