a lame explanation or excuse is weak and difficult to believe
〔解释或借口〕无说服力的,站不住脚的:

lame excuse / explanation
She gave some lame excuse about missing the bus.
她找了个站不住脚的借口,说是没有赶上公共汽车。
a lame attempt to deflect criticism
转移批评的一个无力的尝试