Smugleaf is the fan made name given to Snivy before its Japanese name was revealed by Kotaku.
"Due to his half-closed eyes and apparent smirk, the green starter is quickly becoming known as “Smugleaf” or “Grinleaf” by English-speaking fans.“Smugleaf is the new trollface!” is a new rallying cry, referencing the face a person might put on while trolling on a forum. And looking at that new Pokémon’s self-contented grin, it isn’t hard to see the appeal."