Sentence:  Athletes are celebrated just for competing. Russian gymnast Anna Pavlova, who recorded an imperfect 0.00 for one of her vault attempts, could try to land a <WSD>photobomb</WSD> of herself mugging in the background of all those photos that will be taken of Phelps lugging around his gold. 
Meaning of the word marked with <WSD> tags:  A photo containing someone or something that is photobombing.