This is part of an advertising hoarding for a ‘new smart app for you and your smart pets’. I’ve no idea what it was for but the original poster showed a white mouse. Must’ve been inspired by Hitch Hikers Guide to the Galaxy HG2G.
It would appear from my Google searches for the actual product being sold that ‘something big has arrived’ is a very popular advertising slogan. I’m sure you can find many more reasons to use this phrase: sizeable babies, surprise birthday cakes, sonic booms.