crafty hippo
An expression commenly used for people who do things secretly or are very skilled at something. It really has nothing to do with hippos, just the fact that hippos are very craft and trixy.
Viviana walks up behind Linnea while she's talking to Veronika and Kaylee
Viviana: Hello Liddea!
Linnea: Ahhhhh!! You scared me vivi, you crafty hippo!
Viviana: Hello Liddea!
Linnea: Ahhhhh!! You scared me vivi, you crafty hippo!