It's Darth Vader SHAMPOO.
The Big Bang Theory Season 1, Episode 1
And also, while we're on the subject,
you recently changed your SHAMPOO.
The Big Bang Theory Season 6, Episode 2
You've convinced me, maybe we should
sneak in and SHAMPOO her carpet.
The Big Bang Theory Season 1, Episode 2
for peeing
in his SHAMPOO bottle...
The Big Bang Theory Season 12, Episode 4
...when she discovers your Luke Skywalker
"no more tears" SHAMPOO?
The Big Bang Theory Season 1, Episode 1