Best advice is to BE HONEST! If they detect that your are lying or covering something up that is what will get you booted. Nobody is perfect, and we have all done stupid things, espically when we are young. Most places would rather have someone with the integrity and balls to admit to that, rather than a person who will lie to get a job they really want. If you go in there and answer every question truthfully, you will be fine ( and you will feel better about yourself, no matter what the outcome of the entire application process). Also remember that is better to not be accepted because of better qualified applicants, not high enough test scores, ect. These things can be improved upon, and you can try again later. If you get a reputation as a liar, your pretty much burned with that department, and any others you try as well if they hear about it. Just be honest, and best of luck.