How I Met Your Mother’s Neil Patrick Harris was guest-hosting on Live With Kelly Thursday with special guest Science Bob, and during their fun experiment, NPH accidentally said the T-word.

And what word might that be, you ask?

Science Bob had Kelly Ripa and the actor inhale sulfur hexafluoride, or as he calls it “helium’s evil twin,” which makes your voice sound extremely deep. While we laughed listening to Ripa’s Darth Vader impersonation and Harris’ Buffalo Bill infamous quote from The Silence of the Lambs, “Put the lotion in the basket,” things got a little awkward when he followed with, “I’ve never sounded more like a tranny in my life.”