An ugly or unpromising individual who grows into an attractive or talented person. Alludes to Hans Christian Andersen's fairy tale, The Ugly Duckling, about a cygnet hatched with ducklings that is despised for its clumsiness until it grows up into a beautiful swan.
In an untenable position. Having no recourse or satisfactory course of action. Or "Up a creek with a hole in the boat". Being in a particularly bad situation can often be described as being "up shit creek, in a barbed wire canoe, without a paddle".