An activity involving physical exertion and skill that is governed by a set of rules or customs and often undertaken competitively. b. often sports (used with a sing. verb) Such activities considered as a group: Sports is a good way for children to get exercise.
Rust is Iron Oxide. Hence, any warnings concerning the ingestion of iron may apply. Ingesting too much iron, whether it be via rust, suppliments, or otherwise, can lead to unpleasant symptoms including nausea and vomiting. Long-term side affects such as liver damage can be associated with excessive iron intake.
Urine is actually pretty toxin free as well, but does contain plenty of waste products and some salts. Drinking it is a bad idea because it would upset the salt and nitrogen balance in the body, and the body would have to lose excessive water (as more urine), in redressing the balance.