Occasionally. It wasn't a daily, or even weekly occurrence. But, in all honesty those pranks were some of the things that helped my early sysadmin experience.
When you have nice, well behaved users you'll not have problems that need solving. When things go awry - that's when you'll need to solve problems... sometimes even without pranks.
Before we had yp set up on the machines, we just copied the password file between them with a note "make sure you change your password on foo" since that was the one we regarded as authoritative and would copy that to bar.
One time, while adding a person to the /etc/groups file for write access to the web server, someone did rcp /etc/groups bar:/etc/password (I suspect it was muscle memory) and, well, now bar was unhappy and wouldn't let anyone log in... or even su to root to fix it. Found someone who had an open terminal and had them do a while 1 sync... and then powered the machine down and brought it back up. It wasn't happy, so started up in single user mode. Just needed to get the password file in there... but the terminal was 300h which didn't have a proper termcap entry for vi or emacs to work. I was a mudder and knew how to use ed... so ed /etc/password and then the contents of the minimal password file were dictated to me. When done, we got it back up and then copied the password and groups files to the proper spots.
Another time (and this was a prank), someone left themselves logged in and someone else created a directory path that was about 3000 characters long. /user/jsmith/I/will/not/leave/myself/logged/in/I/will/not/leave/myself/logged/in/ ... The problem with this is that `rm -rf` won't handle paths longer than 2048 characters long. So it didn't get removed "I'll do it later." You know what else doesn't like paths longer than 2048 characters long? fsck. So when the machine was rebooted/crashed at some point, the root volume (yea, user directories were on the root volume) failed to fsck... and failed to mount. Stuck in single user mode with the backup partition and reading the man pages for mount on the other machine we found how to force a mount without fsck and then had the guy who did the extremely long path fix it (and promise not to do it again) and got machines working.
When you have nice, well behaved users you'll not have problems that need solving. When things go awry - that's when you'll need to solve problems... sometimes even without pranks.
Before we had yp set up on the machines, we just copied the password file between them with a note "make sure you change your password on foo" since that was the one we regarded as authoritative and would copy that to bar.
One time, while adding a person to the /etc/groups file for write access to the web server, someone did rcp /etc/groups bar:/etc/password (I suspect it was muscle memory) and, well, now bar was unhappy and wouldn't let anyone log in... or even su to root to fix it. Found someone who had an open terminal and had them do a while 1 sync... and then powered the machine down and brought it back up. It wasn't happy, so started up in single user mode. Just needed to get the password file in there... but the terminal was 300h which didn't have a proper termcap entry for vi or emacs to work. I was a mudder and knew how to use ed... so ed /etc/password and then the contents of the minimal password file were dictated to me. When done, we got it back up and then copied the password and groups files to the proper spots.
Another time (and this was a prank), someone left themselves logged in and someone else created a directory path that was about 3000 characters long. /user/jsmith/I/will/not/leave/myself/logged/in/I/will/not/leave/myself/logged/in/ ... The problem with this is that `rm -rf` won't handle paths longer than 2048 characters long. So it didn't get removed "I'll do it later." You know what else doesn't like paths longer than 2048 characters long? fsck. So when the machine was rebooted/crashed at some point, the root volume (yea, user directories were on the root volume) failed to fsck... and failed to mount. Stuck in single user mode with the backup partition and reading the man pages for mount on the other machine we found how to force a mount without fsck and then had the guy who did the extremely long path fix it (and promise not to do it again) and got machines working.