Irish practical joke
To covertly acquire someones schoolbag, turn it inside out, replace the contents and return the bag to owner, without them noticing.
To really go for it, you can also turn their pencil cases, folders and even sandwiches inside out. When properly executed, there is no prank like a good debagging.
Warning: Debagging someone can trigger a wave of retalitory debaggings, which can trigger a full scale "debagging war" within the entire school. Some particurally epic wars have been known to go on for several weeks.
For the ultimate thrill, try debagging a teacher during class!!!
That wank-stain John just debagged me.
Want to start a debagging war?