Young adults in regular neighbohoods.
If you wan't to have all the freedom of being a young adult, without the hassle of university all you have to do is:
While you are in your chosen university bring up the cheat window (Ctrl+Shift+C)
and type in "aging off", this will not stop the term bar progressing, but when you graduate and move back to the regular neighbourhood your sims will not grow up.
For the disbelieving amongst you this is true you can do literally anything!
Added by: Stuart-Knapman Mar 29th 2005, ID#6243