1. mildly vulgar Broken or malfunctioning; dead, falling apart, or ceasing to work. ("Tits up" is sometimes hyphenated.) Sorry, Mark, I'd love to give you a lift to the airport, but my car's tits up on me again. It looks like our co-op might be tits-up if we aren't granted a license for our communal work premises.

2. mildly vulgar By extension, having a poor, undesired, or ruinous outcome; failing completely or not coming together at all. We were all set to have our picnic on Saturday, but the weather went tits up, and we had to cancel at the last minute. The merger deal between the two companies turned tits-up when it came to light that one of the CEOs had been dodging tax obligations for several years.