Raj Cures His Selective Mutism

Until the season six finale Raj's defining trait is selective mutism: he cannot speak to or around women outside his family unless he has had alcohol or medication, a condition he names himself in "The Cornhusker Vortex". In the finale he laments to Penny without having had a drink since the night before, and the friends realise he is finally cured. He later speaks to Penny sober as a matter of course, and had earlier taken Lucy on a first date to a library where they texted each other instead of talking.