block on

block on (something)

To suddenly forget or be unable to recall something. I can't believe I totally blocked on her name earlier when I've known her for years!
See also: block, on
Farlex Dictionary of Idioms.

block on

v.
To forget or fail to remember something; have a mental block about something: I had met these people before, but this time I blocked on their names.
See also: block, on
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • block on (something)
  • blank on
  • blank on (something)
  • put a name to
  • put a name to (someone or something)
  • put a name to somebody/something
  • wrack (one's) brain(s)
  • wrack brains
  • rack brain
  • rack brains