Creating tight biceps without weights (and of course without any banned substances) is feasible. Exercises that require you to support your bodyweight with bent arms work the whole arm and the shoulder muscles (deltoids). A simple towel is very effective. With a partner hold either end and pull as in a tug of war to pump up the biceps and chest. This is one great way to build up the biceps. Another way to build the biceps, is by using a bar (as is standardly used for chin ups). The speed, repetitions and intervals between sets also play a part in how your biceps develop...and the food and drink we ingest.
Here is a link from a man who is living proof that biceps without weights is a reality (nice and easy).
How to get big biceps with bodyweight exercises! Only 3 exercises!