The adverb “really” acts as a general intensifier, so it can be placed almost anywhere in a sentence. Examples:
Really, coffee and donuts are the best combination.
Coffee and donuts really are the best combination.
Coffee and donuts are really the best combination.
Coffee and donuts are the really best combination.
Coffee and donuts are the best combination, really.
Really, coffee and donuts are the best combination.
Coffee and donuts really are the best combination.
Coffee and donuts are really the best combination.
Coffee and donuts are the really best combination.
Coffee and donuts are the best combination, really.