Another oft-quoted Cassidy gem is the word scam, which Cassidy linked to the phrase is cam é or ’s cam é, meaning ‘it’s crooked’. This is a slightly odd phrase, though it is possible that someone would say it. The problem with this is that it is a phrase. Why would someone who was bilingual in Irish and English use a phrase rather than a word like caimiléireacht (which means fraud or deception)? So a bilingual person saying ‘It’s a ’s cam’ is really saying ‘It’s a it’s crooked’. Highly unlikely.
Back in the real world, scam probably comes from the Spanish escamotear, which is defined as:
to palm, to conceal; to lift, to swipe; to cover up.
Here’s a definition in Spanish from wordreference.com. The second example essentially means ‘they stole a thousand pesetas from me in front of everybody.’
1.tr. Hacer desaparecer algo mediante un hábil juego de manos de manera que los presentes no se den cuenta:
el mago escamoteó un par de palomas y un conejo.
2. Robar o quitar algo con agilidad y astucia:
me han escamoteado mil pesetas delante de todo el mundo.
3. Eludir, evitar, suprimir intencionadamente:
cuando habla de su marido no escamotea elogios.
This is a much more likely candidate, as the meaning is exactly right and you don’t have to put two words together in order to make up a suitable phrase. All the letters are there in escamotear!