I like the following two ambiguous sentences: Buffalo buffalo buffalo buffalo buffalo. and: Police police police police police. There are multiple ways to parse these sentences. Tom Dan Asimov writes:

There are also the interesting sentences

"I love her cooking"

and

"Colorless green ideas sleep furiously"

among others.

—Dan

Veit Elser wrote: ----- ... two fine examples showing how even parts of speech can be ambiguous:

“Time flies like an arrow” “Fruit flies like a banana” -----