Instead of having Rivka handing him a drink, Eliezer apparently wanted her to hold the pitcher while he drank from it. That would be considered odd and kind of rude today and it was no less so in Abraham’s day. We all know that Eliezer was testing Rivka’s attribute of kindness but Rabbi Joseph B. Soloveitchik explains that he was also testing her patience with outrageous requests. Rivka passed both tests with flying colors. (From Abraham’s Journey, cited in the Mesoras HaRav Chumash.)