a stick in the mud字面意思是烂泥中的树枝，引申为老古董；老古板；无心上进的人。

【例句】
Ginny is such a stick in the mud. She never wants to try anything new.
詹妮是个老古板，她从不想尝试新的东西。

You may regard my husband as a stick-in-the-mud, but on my part I like his personality of that kind.
你可以说我的丈夫是个老古董，但是我倒很喜欢他的这种性格。