'let on' definitions:

Definition of 'let on'

From: WordNet
verb
Make known to the public information that was previously known only to a few people or that was meant to be kept a secret; "The auction house would not disclose the price at which the van Gogh had sold"; "The actress won't reveal how old she is"; "bring out the truth"; "he broke the news to her"; "unwrap the evidence in the murder case" [syn: unwrap, disclose, let on, bring out, reveal, discover, expose, divulge, break, give away, let out]

Synonyms of 'let on'

From: Moby Thesaurus