A plunger isn't your only option to unclog a toilet. If you don't have a plunger handy, you can try using a bucket of water and physics to unclog it. If the water in the bowl is low, you can fill a bucket or trash can with water and dump into the bowl from approximately waist height. This can force the clog through, although it can create splash-back.
If a plunger doesn't work on a clog, you may need to resort to a toilet snake (with rubber padding to avoid damaging your toilet). This will work the clog through the system.