Full Idea
The Strengthened Liar sentence says 'this sentence is not true in any context'. It is not hard to figure out that there is no context in which the sentence can be coherently evaluated.
Gist of Idea
Strengthened Liar: 'this sentence is not true in any context' - in no context can this be evaluated
Source
Leon Horsten (The Tarskian Turn [2011], 04.6)
Book Reference
Horsten,Leon: 'The Tarskian Turn' [MIT 2011], p.58