There are times when people need to make their sports shirts, such as hockey jerseys, smaller. Sometimes, people buy hockey shirts in the smallest size offered by a retailer, but the shirt is still not small enough for the wearer. Or, perhaps they are gifted a larger-size jersey that they cannot return. While it's true that many fabrics undergo shrinkage when washed and dried, hockey jersey materials such as cotton and polyester can often get dramatically smaller.
Wash your hockey jersey in the washing machine on the hottest temperature setting. Under normal conditions, for a cotton and/or polyester hockey jersey you don't wish to shrink, you would wash it on the coldest temperature setting.
Dry your hockey jersey in the dryer on the hottest temperature setting.
Remove your jersey from the dryer and determine if you wish to have an even tighter fit. Repeat the washing and drying on the hottest settings until you get the desired fit.