It grants permission, even if permission was not required or sought. This can be used to admonish, praise, chide, tease, or approve, depending on the context.
"I lechoo"'s negative form is "dunlechoo".
Your response: I lechoo taste my otoro (fatty tuna)
There's a female sunbathing by the pool. A dirty old man walks up and stands next to her, staring.
He says: Hey baby, I lechoo be all hot n'stuff, aye?
Her response: I dunlechoo get it up, sick perv. deploying her pepper spray
So, you see, there's really a wide range of uses for "I lechoo" - we've all discussed how odd it is that people always answer the phone with the ubiquitous "hello," well next time the phone rings pick it up and answer with "I lechoo," and I by all means lechoo. This lets the caller know that you're ready for talking and you don't want to spend those precious moments checking to see if the call actually went thru like they used to do "back in the good ole days" - with their sorry "hello" babble. I can think of infinite possibilities for this phenomenal conjuncture, but I'll leave it up to your imagination to begin applying it to whatever you feel is appropriate. Let's watch history develop and evolve, I lechoo.
You: "Ahh, sure, I lechoo get me a New Castle."
AGREEMENT: "I'd like to tap that ass." "Ilechoo."
DESIRES: "Ilechoo give me all your weed."