An outright traffic light race challenge? Never. Once in while someone next to me at a light will take off really hard, much harder than normal. Not sure if it's due to my presence or not. I always ignore them and do what I do. I drive pretty close to the speed limit on straight roads, so it's rather common for someone to come up from behind wanting to get by. I'll oblige them once it's safe.
On twisty roads, nothing has ever come up from behind. Ever. Well, there was this one sportbike once, I let him by, even though he probably didn't need the help.
What I don't get are people driving below the limit on no-overtaking single carriageways, a huge tailback behind, driving on past a dozen lay-bys. Selfish little *@!#%s! What amuses me is the other sort. You come up behind them, and they suddenly speed up dramatically. Are they trying to gap me, a type of race? Or are they just being considerate and decide to drive at a decent rate? On straight roads, I don't care, as long as they stay out of my way. On twisty roads, no one has ever gapped me. Ever. They usually either turn off or give up at a lay-by. Or the worst, they give up and go back to driving really slow, ignoring lay-bys. WTF?? That's the worst. Talk about sore losers!