Sucking a lemon 

The look of disgust in a person that is reminiscent of the face pulled when eating something very tart, such as a lemon.

When my wife discovered that the paedophoilia charges that she had laid against me would not be pursued as the prosecutor had found them to be baseless she had a face like she was sucking a lemon.

Sucking a lemon by stropmag July 10, 2010

Trout sucking a lemon 

when someone tries to pout seductively, however the result is a painful grimace, like one is struggling in their attempts to look seductive.

Everytime Eimear is in a photograph she looks like a trout sucking a lemon.

Trout sucking a lemon by Dirky McDiggler August 11, 2011