A name used to describe shitty teachers and/or old people. People with this name usually hate students and refuse to teach classes themselves. A Leischner is usually fond of old technology and hates to be reffered by his/her first name.
"Hey Mr. Leischner, can you teach me something NEW?
"Hey Mr. Lieschner, why do you use shitty ass computers from the eighties?
"Why the fuck does everyone fail your class?"