I smoked two cigarettes. will it show up on a urine test 4 days later?

No: No, but don't smoke. Healthy lifestyle can prevent lots of problems.

Depends on the test.: If you smoked tobacco cigarettes, then the answer is no, since this is not tested for in any standard urinalysis or toxicology screen. If you smoked marijuana, then a urine drug screen will almost always be positive for thc 4 days later. A regular physician urine dipstick and urinalysis does not look for drugs, so the test must be a specific urine drug test.