Here are the legends that used to exist in the USSR...
1. Metro. Doors are about to close. A civilized person - in a tie, indispensable detail - wants to get in, the doors are closing and his head is already in the subway car and stuck in the doors and the rest of the body is still on the platform. He looks sadly at those who are in and says in the fallen silence - "That's great! F*** underground!"
2. Kvass trailer tank. A kvass trailer tank turned over (usually in an accident) - and on its bottom were giant gentles (cestodes, another alternative - a corpse).
3. Foreigners - wreckers. They gave Soviet children sweets (or chewing gum) infected by tuberculosis or syphilis (alternative: farced with needles or pieces of razor blades, more exotic alternative: farced with baleen). Probably this legend was told by grannies for educational reasons in order children wouldn't take anything from strangers.
Instead of foreigners might be prisoners, they left bandages with tuberculosis phlegm in the playgrounds.
4. Foreigners sold black marketeers jeans infected by syphilis. The last ones sold them to unwitting fellow citizens. Usually on the back seam there was a package with flea (lice) scaring poor people at first jeans wash.
5. The story about some pioneers parade in Red Square. They said the pioneers were parading doing their best and vile foreigners were throwing provocative gum under their feet, allegedly to break their formation. No effect! Such consciousness!