My husband made himself a T-shirt that says “I went to Llanfair PG and all I got was this lousy T-shirt” in Welsh (with the whole name written out). He did the translation himself, and came up with “Bues i yn Llanfair PG ond ces i mo’r crys ofnadwy hwn.” I’d like to find out how a real Welsh speaker would say it.
Best I van do is “Es i Llanfair PG a phob Cawn oedd hyn T-shirt drwg”
His back-translates to “I was in Llanfair PG, but I didn’t get this terrible shirt.”
“Bues i yn” is more like “I have been in.” I would say “Es i i Lanfair PG” (lit. I went to Llanfair PG—note the mutation.)
“Ces i mo’r crys” is a very colloquial way of saying “I didn’t get the shirt.” I would suggest “a ches i ddim ond y crys ofnadwy hwn,” which is “and I only got this horrible shirt.”
“Ofnadwy” is “horrible, terrible, scary.” I would probably go with “gwael,” which is more “base, vile, nasty.”
So: Es i i Lanfair PG, a ches i ddim yno ond y crys gwael hwn.
But I’m not a native speaker, so YMMV.
Thanks! 