Would you get this joke?

[DottyDotDot81]

“I’ve just been on a once in a lifetime holiday ... never again!”

I made a twat of myself asking where they went 😞

Yes HobbyIsCodeForDogging* Lourdes is a place famous for someone seeing an apparition of the Virgin Mary there - exactly right!

I was told that joke by a very drunk priest, during a pilgrimage to Lourdes

I don't get the elephant/frog one.

It took me a minute to get that! I think it would be more obvious if spoken, as others have said.

For those confused: the destination doesn't matter. The point is the once in a lifetime/never again bit. OP, I suspect that if you're a literal sort (and you might well be, on an Aspergers forum!) then you might struggle to understand the humour in it initially.