Teaching English to terrorists unintentionally could be grounds for detention as an enemy combatant at Guantánamo Bay, according to US government lawyers.
The assertion was made by Deputy Associate Attorney General Brian Boyle during federal court hearings last month into the supreme court's ruling on the right of Guantánamo prisoners to challenge their detention in US courts.
According to Associated Press, when asked by Judge Joyce Hens Green if a hypothetical resident of England who teaches English to the son of an al-Qaida leader could be detained, Boyle said he could because "al-Qaida could be trying to learn English to stage attacks there". Boyle compared that aid to "those shipping bullets to the front".
Source - The Guardian
I guess the only way to protect yourself is to refuse to teach words like, bomb, kidnap, ransome etc...