Where to start - so many gems to choose from.
Saskia and Maxwell in BB6 - both cheered hugely when the whole house were up in week 2, then evicted back to back with huge boos a few weeks later.
Kathreya - I liked Kat, but the drama of this eviction was through the roof. Rachel and Darnell acted as if she'd just been sentenced to death.
Rebecca - An underrated eviction that doesn't get mentioned on here enough. She'd spent then entire week (as had Luke, Dale and Stuart) gloating over how Darnell or Mohammed would leave. The look on Luke's face when Rebecca's name was called was priceless. Then he tried justifying it by claiming it was a "three way voting split", when in reality she had 60+ % of the vote.
Grace - goes without saying.
Kirk and Natalie - cheered and then evicted. Plus Natalie's "they must have thought they were voting to save me" justification was the icing on the cake.
Winston - just because it's always great when a dull housemate doesn't coast to the final. Plus Ash and Helen had laughed off the one lone "Get Winston Out" voice, only to have him evicted seconds later.
Kris - he had said, before that week, that Freddie was only surviving so many evictions because he was up against "weak competition". The following week, he lost to Freddie.
Classic.
Aron - Mainly because Deana was saved first, much to the dismay of Conor.
But the best, by some considerable distance, is still Sezer - nothing will ever top that for me. The look on his face, the fact that he was so boastfully confident beforehand, all adds up to the ultimate eviction.