roll right off one's tongue 舌头上滚下来-----顺口
trip over one's own tongue 打磕巴,trip除了“旅行”还有“绊倒”的意思
拗口的东西则是“a tongue twister”(不仅仅是绕口令啊~)
拿“奔驰”这个名字举例:
The Chinese translation“奔驰”rolls right off the tongue. However, if we call the brand 梅赛德斯·本兹, that's a tongue twister! It's like I'm tripping over my own tongue when I try to say it. 汉语翻译过来的“奔驰”说起来很顺口,但如果说它的全称“梅赛德斯·本兹”就很拗口!说的时候我感觉我的舌头都要打结了!