The phrase "frivolous things" refers to things that are considered unimportant, silly, or not serious. They are often irrelevant to the main matter or of little value. Full definition
Plus you'll have less temptation to spend the money on frivolous things because it will be hidden away inside your TFSA. (moneysense.ca)
Most people do not invest the extra income they would have from refinancing but instead use it for frivolous things will no actual return. (biggerpockets.com)
At the end of the day, yes, clothes might be a totally frivolous thing to many. (cominguprosestheblog.com)