Y Combinator makes something people who make something people want want.

Y Combinator (YC) is the most influential startup accelerator in Silicon Valley. It provides seed funding, mentorship, and networking to early-stage tech companies in exchange for equity. Famous alumni include Airbnb, Dropbox, Stripe, Reddit, and Coinbase. Its founder, Paul Graham (who wrote this tweet), coined YC's core mantra: "Make something people want." This joke tweet plays on that phrase recursively — YC's "product" is startups, so YC makes something (startups) that people (founders) who make something people want (their own products) want. It's an inside joke about YC's mission statement and its self-referential nature as a meta-company built on helping other companies get built.