I suppose it depends on just how badly you think she is pressed for rent. If she's buying tatoos, it doesn't sound like she's so pressed that she can't go pawn something.
I'd sympathize, and tell her you're a bit short on cash yourself. Why, just last week you'd had to put money down to reserve that vacation flight/room/whatever ... too late to get that back now ... You're gonna be a bit strapped for a couple months
Is this really a friend in dire need, or someone who's foolish with their money but who could come up with it if she really tried?
I worked my way through college, and I always made sure I had my rent covered first. Any time I got extra hours or found an extra short term job, the first thing I always did was stock up on canned food, rice, and other staples that would last.
I always seemed to have a housemate who was short of cash for rent, and "borrowed" my food, shampoo, soap, whatever wasn't nailed down, but had money for smokes and beer.
One of my spoiled housemates got his "allowance" cut off when he got suspended for a semester for his grades. He lasted a few months sitting around doing nothing, but he eventually ran out of cash and people to borrow from. Getting a job as a dishwaher was probably the best education he got in his academic career. Did him a world of good.
If your friend and her spouse are both working, and there's been no huge car repair bill or medical bill that just hit, she's probably got the means to find a month's rent. Maybe pawning something would be a good lesson in planning ahead and putting off the next tatoo.
True compassion if she really needs it is a good thing, but enabling foolishness isn't helping her out.