I say this every time I make an "oops," even though the saying is 'whoops-a-daisy.' Reason being one day at work (previous job), a friend and I decided we would substitute different flowers for the daisy each time we made a typographical error during catalog production. We would shout out "whoops-a-lily" (which stuck in my brain), or "whoops-a-petunia" or "whoops-a-pansy" ... The earlier terms 'upsy-daisy,' 'upaday,' etc., appear to be the source of the term whoops-a-daisy although they have different meanings. The 'daisy' part is a fanciful extension of the word day. The name daisy itself derives from the word day. The daisy flower, which closes at night and exposes its yellow center in sunlight, was thought of as the day's eye. Upsy-daisy and derivatives were exclaimed when a child, in play, was assisted in a spring-leap from the ground (up from the daisies). The expression 'Whoopsie Daisy!', is first recorded in the New Yorker, in September 1925 and means to publicly acknowledge a mistake. It is now also exclaimed whoops-a-daisy, or whoops or oops. That's a lot of whooping.
Anyway, these are all blooming in my garden right now and I have fun walking around "whoopsinging" all the day long.