Tent: A 2 person tent divides up really well between Tent/rainfly, and poles/groundcloth, a 4 person tent breaks down each component even more. Share with a bigger tent and you should be good to go
Sleeping Bag:
Go in the summer months, when the temperature will be warm. I live in the Mid-Atlantic, and typically take an Army Surplus Poncho liner as my sleeping bag on trips in the late spring-early fall. In the height of summer, I bring a cotton sheet (I know, cotton is bad, but it's all I got).
Sleeping Pad:
If you are careful about your sleeping spot you don't need one of these. However, it's always the first "luxury" item that I pack. I won't camp without my mattress. If you can, however, I'd loan mine to the newbie friend, or use a spare/borrow one from a friend.
Stove:
Most backpacking food reads like: Boil X volume water. Add powder. Stir. Let sit Y minutes. Plan to share food/utensils, and you should be good to go.
Food:
Again, double up and plan to cook/eat 2 person meals instead of 2-1 person meals.
Eating Utensils:
All the friend would need is the bowl and spoon. Bowls can be repurposed from frozen dessert topping containers, large butter/margarine tubs, etc. Sure, it will fall apart after a few uses, but you can't beat the price
Water Bottles:
If you know anyone who beverages out of plastic bottles, collect and reuse them. Wash them out and use as water bottles. I've personally used 1 liter soda bottles for months before they wear out. Best part, it's free (assuming you'd drink the soda/water/juice to begin with).
Backpack:
Either borrow a full pack from a friend, or pack as much as you can in your pack and have him bring along the biggest backpack (daypack) he has. Alternate days.
One final note:
You can rent almost all the gear needed from a local REI. I'm not sure if you need to be a member (recommended if you will be buying a lot of gear), or if they will rent to Joe Public, but worth looking into.