I guess using liquid draino isn’t the safest nor environmentally sound choice and for bathroom sinks, you might just be able to unclog your drains/pipes simply by cleaning the U-pipe attachment. Not a bad solution plus it will save you some money buying that toxic, chemical stuff or calling your local plumber.
The steps of this instructable show you how to remove biological mysteries from your sink’s drainage without using caustic chemicals that cost money, are bad to breathe, less fun and whose success as an unclogging strategy has a lot of uncertainty.