Story varies with every year in college.. I'll start with my first year. Various branches study together in their first year. I belong to ECE and we used to have classes with Agricultural engineering branch students. There were more than 100 students per class so it was difficult for teachers to keep a check on every student. Some teachers were very strict. They used to maintain their attendance register very well and if anyone is caught during calling out a fake attendance then they suspend such students from their classes. But some teachers were not that strict. One such teacher was our computer teacher. One day, there were kind of less students in class and my friend said me to proxy. Her ID was before my ID. I said her attendance and that teacher looked at me..but when it came to my turn teacher again looked at me and i had to be quiet in my turn. :(
Well this was just a short part.
Some of my friends used to enter the class from back door during the end of class in attendance time and lucky they have been that they were never caught doing this.
After 1st year, we study branchwise ..teachers keep track of every student. And it becomes very difficult for us to proxy. Although when teachers said us to give attendance in paper we used l fill paper with full attendance when 30's of students used to gt absent.