Typically used in video games from Fighting to madden. To go into practice mode and learn things, typically combos or plays.

Past Tense: Labbed
Future tense: Going to lab

Got the covid-19 vaccine

To practice dance

Labbing for competitive Madden gamers is going into practie mode aka "The Lab" and finding money plays and dominating blitzes or by playing unranked matches against friends to find plays and how to make hot routes that will dominate your opponent.

the state of working on a lab writeup which is all pain no gain

shortened-coloquialism for elaborating or an elaboration.
To elaborate the truth therefore to lie / be lying.

a. Verb: to lab; labbing
b. Noun: a lab.

clubbing for the lab nerds