blank spark
A person who when faced with a stressful situation or under direct questioning fails to either take appropriate action or to make an appropriate response.
Erica: I asked him for a date.
Rose: What happened?
Erica: He went red, didn't say anything and ran off
Rose: He's such a blank spark.
Rose: What happened?
Erica: He went red, didn't say anything and ran off
Rose: He's such a blank spark.