I have responded to this question before, I call it a "disease," and I have to do this to all show tune partial phrases that I heard. I go into a sorta trance until the lyric races through my brain, I realize why I know it, and then I complete the phrase.
The worst, and most continuous was when I worked in a restaurant with a manger named Mark, and every time a server needed him they would run back in the server alley and yell, "Mark, Mark..." And I'd have to say, "I'm Mark."
"I've missed you these days, I thought you might call. It's been weeks"
For those who thought NEXT TO NORMAL wouldn't have a life outside Broadway, well it's now playing in 4 cities, 9 different countries and has been translated into 6 languages.
of course I have a few from A Chorus Line. Anytime it's been a long day at work I'll say "Can we smoke?? Can the adults please smoke??" yet I don't smoke. Or if the lights are too bright I'll say "that light, do you have anything softer?".
And then there's my frequent one when people say "Hello" and I'll respond with "Hello, Dolly!".
A Chorus Line revival played its final Broadway performance on August 17, 2008. The tour played its final performance on August 21, 2011. A new non-equity tour started in October 2012 played its final performance on March 23, 2013. Another non-equity tour launched on January 20, 2018. The tour ended its US run in Kansas City and then toured throughout Japan August & September 2018.
The Jesus Christ/Superstar one is probably the one I do most often.
There's also a commercial that I see sometimes on TV that starts off with "I never asked for this." and I always finish it in my head with "Or planned it in advance."