What are the chances for chlamydia with a random dude?

High. Chlamydia is very prevalent in the population of young sexually active males and females. In addition, hpv and herpes are widely disseminated. Condoms may reduce the transmission rate, yet they are not perfect. If you have any symptoms such as a discharge or pelvic pain, get checked.
Chlamydia. That is like asking "what are the chances i will shoot myself if i play russian roulette?" the answer is that the odds of contracting chlamydia are too high to leave things to chance. Don't take risks with your physical & emotional health or with your ability to reproduce in the future.