Some of our best friends don't know how to use lie and lay correctly, and we still love them. We also never point out their errors (after all, they're not rich and famous people who deserve a slice of humble pie every now and then). We do correct our students' grammatical errors. And they like it!
Now for lie/lay....
In the present tense, the difference between lie and lay is easy. Lay requires an object -- something that gets laid (stop snickering in the back, teenagers).
- "Now I lay me down to sleep."
- "Lay an egg, mother clucker!"
It's trickier in the past tense. This is because "lay" is the past tense of "lie."
We still remember our fifth-grade teacher trying to explain this to us. He lay on the floor, telling lies. (It didn't make sense to us, although what he said about his nose hairs was both memorable and hilarious.)
In short, mnemonic devices just don't help us all that much. Straight-up memorizing does.
Present Past Participle Past participle
Lie --> lay --> lying --> had lain
Lay --> laid --> laying --> had laid (always requires an object)
More on this, from someone who's created an elaborate scheme for remembering the difference.