McBiota is a fast-food restaurant toy that can measure the compatibility of two people's microbiomes, serving as a litmus test for their romantic potential. This work envisions a world where microbiome-based healthcare is prevalent and there is an increasing emphasis on productivity and efficiency. People use microbiome science as a benchmark for relationships. Fast-food love, like fast food itself, prioritizes "immediacy" and "convenience." Rather than spending a significant amount of time navigating and negotiating traditional commitments, people choose a more efficient method to determine their partners. Microbes, these external cells that coexist with our own cells, each make up about half of our bodies. Can we still call ourselves individuals, or are we walking kingdoms inhabited by mutually beneficial microbial communities? A kiss can transfer 80 million microbes between people, and cohabiting partners share skin microbiomes to a significant extent, meaning their microbes move into each other's bodies. If we view individuals as "realms," then when two people engage in romantic relationships, is it similar to the marriage of kingdoms? In this context, the harmony between the two microbiomes becomes crucial, a matter of life and death for the microbes, and it also affects the host's health and emotions. McBiota reflects on a new perspective on how humans view their bodies—as ecosystems where microbial balance is key. It also contemplates the evolution of finding partners, from arranged marriages to online dating, progressing to a more utilitarian form of love.