On the 1st campus you will get email to buy Double Jump Beds & Love Benches, 2 Player Arcade Machines & Indoor Tables (make a big student lounge to place loads in) , Just buy plenty of them and you can earn this achievement.
There are other items just look for things that say good friends. I bought a new building an made a massive lounge an filled it with those items an vendors with no bins for the 1000 litter achievement on the 1st campus, also made more dorms an classes.