The antonyms for "blow-ups" are implosions, deflations or collapses. An implosion is when something is sucked inward or collapses in on itself, rather than expanding outward like a blow-up. Deflation describes the process of something becoming less inflated or reducing in size, as opposed to expanding like a blow-up. Lastly, collapse refers to the sudden falling apart or failure of something. These antonyms contrast the positive connotations of "blow-up" which suggest growth, expansion and increase, with negative associations of shrinking, reduction and failure.