Be no laughing matter
Definition 1 of 1
Pro Tip 1/3Emotional Weight
Use to express concern or empathy towards serious situations. 
After the hurricane, finding shelter for everyone is no laughing matter.
Pro Tip 2/3No Humor
Highlighting that humor is inappropriate when discussing the subject. 
When she spoke about her illness, I realized it was no laughing matter.
Pro Tip 3/3Issue Severity
Indicates the issue should be taken very seriously. 
The company's bankruptcy is no laughing matter to the employees.