primarily used as an adjective, or an interjection.
Kake: "
Dude, you make some crazy grilled cheeses."
Billy Ice: "Yeah man, my grilled cheese is so OH YES SIR!!"
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"I have no idea what I did last night. OH YES SIR!"
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"Man, that
girl looks so OH YES SIR right now."
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Alternatively, OH MY GOD YES SIR can be used for a more dramatic effect.