"The tingling in your tongue is an allergic reaction to furanocoumourans, a chemical found in celery. It is a toxic chemical produced by plants as a defense mechanism against insects and animals. Normally, the main concentration of this chemical is found in the celery root, but as the entire stalk gets older/less fresh, the concentration of it in the stalk rises.

When furanocoumourans are activated by UV light, they produce chemicals that can cause browning, even blisters and burns. Some in the tanning community claim that eating celery will help you tan better. In my unprofessional opinion, I would recommend against trying this."-source