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i find this quote hilarious "2+2=5, (for extremely large values of 2)"

but the meaning is far beyond being a funny quote ...
it's originally a Communist slogan in the USSR referring to the five-year plan to increase production. It originally meant the goals of the five-year plan could be achieved in four years if the people would try hard enough. It also re-enforces the communist idea that by working together, more can be achieved than working individually.

mathematically when we talk about rounding and estimating. For instance, suppose you have your calculator set to round all numbers to integers (no decimal places) and you're actually computing 2.48 + 2.47. The calculator will automatically round, so 2.48 & 2.47 will show up on the screen as 2. Then when you add, the sum 4.95 will be rounded to 5. Hence, 2 + 2 = 5 if the value of 2 is large enough.

It's a joke ... but a joke with a somewhat serious point. All measurements in the real world (as opposed to the esoteric whirled of mathematics) are estimates; they're always rounded to something. There's no such thing as absolute precision. So rounding must come into play sometime or other, and the joke about 2 + 2 = 5 if 2 is large enough, is a reminder about the way that estimation errors compound.