U.K. Reality Star -- OBLITERATED BY RUGBY PRO ... Hospitalized, Cracked Ribs

This is BRUTAL ... and also very, very awesome.

British reality star Jamie Laing -- one of the stars of "Made In Chelsea" -- got absolutely annihilated during a charity rugby match in London ... all thanks to a former member of the All Blacks.

The guy who delivered the blow is Brad Thorn -- who just retired from pro rugby 3 months ago ... but decided to participate in the Rugby Aid charity match.

Long story short ... Laing tried to run across the pitch, encountered Thorn -- and GOT ROCKED HARD!!!!

Props to Laing for trying to tough out the hit -- but the guy was eventually hospitalized and diagnosed with cracked ribs.