The 'Not Yet, Ferb' meme originates from the popular Disney Channel animated series, Phineas and Ferb. In the show, Phineas frequently uses this line to hold back his brother, Ferb, from starting one of their massive inventions or projects until the timing is exactly right. Online, the screencap has evolved into a relatable reaction image used to illustrate situations where someone is overly eager to start an activity, spend money, or celebrate an event prematurely. It perfectly captures the tension between extreme readiness and the forced necessity of waiting for a specific trigger or time.