What did the soap say to the bartender?

The joke “What did the soap say to the bartender? Give me some subs and put it on my tab” is a play on words that blends elements of a bar setting with terms related to soap and bathing. In a bar, it’s common for customers to have a “tab,” an ongoing record of their charges to be paid later. The soap, being an inanimate object humorously personified in this joke, twists this concept. Instead of asking for alcoholic drinks and putting it on a “tab,” it asks for “subs” (a play on “suds,” referring to soap bubbles) and requests to put it on its “tub” (playing on the similarity in sound between “tub” and “tab” and referencing a bathtub, where soap is typically used).