The knife you used to make a peanut butter sandwhich that you set near the sink, because you’re not sure if you’re done using it. Can be used metaphorically to refer to something else.
•“Hey don’t do dishes, my peanut butter knife is by the sink. I might be hungry later.”

•“If you don’t want to be friends with her again why don’t you just deny her friend request?”
“Well, I might want to sleep with her again at some point sooo, lol. *shrug* She’s my peanut butter knife.”

“I made sure to leave on good terms with my old job in case I need them to be my peanut butter knife next summer.”
by But Sects June 15, 2021
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Used to spread peanut butter onto toast , not the butter knife for uncultured swine out there ...... strictly for the cultured world and used strictly for peanut butter !
Jordan used a peanut butter knife to spread the heavenly smooth peanut butter onto his toast , because he was a well cultured individual !
by chuckiepoo March 14, 2016
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