Being a mother of three ain't easy!

Kourtney Kardashian could hardly keep her eyes open during a family outing to the farmers' market on Sunday. Kids Reign, Penelope and Mason kept her busy, even though she had a friend along with them, and poor Kourt looked like she was about to pass out!

Speaking of passing out ... on last night's episode of Keeping Up With the Kardashians, Kourt was raging in Mexico for her birthday celebration -- which was shot a couple months ago -- and bragging out throwing up in her bed and passing out in her puke! Who knew the mother-of-three could rage like that! Meanwhile, baby daddy Scott Disick was jealous and pissed off that his baby mama is allowed to party like that and not get sent to rehab, as he said he would have been. Funny what a different a few weeks makes; I don't think Kourtney even gives a sh*t if Scott goes to rehab at this point; she OVER IT! She's calling his hook-ups hookings (Sofia Richie) and seems to have just completely given up on the Lord. Anyway, check out this scene, which really feels like a throwback at this point ...