The phrase "monkey around with" generally means to play or tamper with something in a careless or irresponsible manner. Antonyms for this phrase include responsible handling, seriousness, and professionalism. If you have been assigned a task, it's important to approach it with care and diligence rather than monkeying around with it. Ignoring the task or treating it lightly can lead to errors, delays, and consequences. It's best to take responsibility, focus on the task at hand, and handle it with seriousness and professionalism. This will ensure that the task is completed accurately, on time, and to the best of your ability.