Why not have one house cook the other dinner? Or (this might be a little bit more difficult) have like a potluck dinner?
Our freshmen had a frosh (somewhat like a function...usually sober activity followed by party afterwards) with Theta's freshmen and they served the girls dinner. All the guys dressed up, went to pick up the Theta's at their house where they all got a rose, and then came back to our house for dinner of salad, spaghetti and bow tie pasta with marinara and alfredo sauce, bread, and ice cream. They also got some sparkling grape juice as wine and then just got to meet each other over a nice dinner in a non pressure atmosphere.
Another idea, and this one would be longer than 30 minutes would be to go to one of your universities lesser attended sports events as a group. Go to the soccer game, or the volleyball match or wrestling or gymnastics or whatever other sport you can get into for free. Make the theme "looks like team spirit", and try to wear the most hideous display of school spirit. Be really loud and crazy. I'm sure the sports team would appreciate the support, and if you kicked out, well what a great story! Think if two members began dating b/c of it and got married...the stories to tell the kids! (I fell in love with your father as we were getting handcuffed....)