blow (something) sky-high

blow (something) sky-high

1. Literally, to destroy something through an explosion. The tanks blew the enemy fortress sky-high.
2. To undermine or negate something completely. I thought I had finally discovered the problem with our experiment, but, when we tested it, the results blew my theory sky-high. Bob was considered for the promotion, but he blew that idea sky-high when he came in late to work each day this week.
See also: blow