It's Just Awful!(1982)

Original title: Просто ужас!

The amusing adventures of sixth-grader Anton Murashov and his father, who were convinced that being someone else was very easy —much easier than being yourself. Anton's friend's father invents a Wish Fulfiller, and with the help of this machine, Anton and Vadim Petrovich switch places; Anton becomes a veterinarian, and his father, a veterinary doctor, becomes a schoolboy...