Try the "Signing-Partner" method. Create a system of signing with a fellow student in the class. This is going to double your knowledge of the subject because you can work together to sign answers to each other. On multiple choice exams:
Establish hand or foot tapping signals for A, B, C, D, E and "wrong answer." By creating a signal for "wrong answer" you are going to improve the likelihood of you both doing well on the test by helping each other eliminate wrong answers. Also create a vocal noise for getting their attention that isn't suspicious (like a cough, or foot tap).
Start by coughing to get their attention.
Use your fingers to give the number of the question (flash 3 than a 2 to with your hand signal question "32").
Wait for them to signal their answer (pulling their ear for "B").
If you need help deciding between 2 answers: cough, give the question number, and signal for the answer you suspect it might be.
He or she can nod his or her head if its correct, if it's the wrong answer he or she can send the "wrong answer" signal (put up your hair in a ponytail).