What does the word suttle mean?

Question

Just wondering, my friends cellphone vibrated in class and my other friend was like 'suttle'

Answer 1

Subtle. he/she was usin git sarcastically. it means unnoticeable or cunning.

Answer 2

Use a dictionary! It is spelt Subtle.

It means cunning in the situation you are describing.  

Answer 3

Basically it's an expression that is used when one has done something without drawing much attention to themselves. But in your case your friends being sarcastic so he said 'suttle' because the vibiration gave you cellphone away> therefore the sarcasm insert. :P