As I understand it, one strategy of checking on interest for a man is to tell the women a stupid joke and to see if she finds it funnier than it should be. Kind of a litmus test for "is she going to laugh at everything I say (that's humorous)?"
It may be that you have a greater sense of humor than most women, which, combined with confidence, comes off as flirtatious. You laugh at what he thinks you shouldn't necessarily find funny, so you must be TRYING to boost his ego? That's just an uninformed guess.
Well girls can be hard to read, especially if we're trying to figure out if you're into us. Often we just hope for the best, lol I guess that's what this guy is doing. Now I feel bad for him! You tease!
Judging by your picture, I'd think your flirting too. Just kidding. Maybe they like you even before you laughed. But for the most part, when a girl laughs, it's a sign that were doing something right. At least most of the time.
There have actually been psychological studies on this. A supermarket (my textbook doesn't give the name) implemented a "superior customer service plan," where their employees were encouraged to smile, laugh, and make polite small talk with customers to "make them feel welcome." Well, it worked. Their customer service ratings shot through the roof and so did their sexual harassment charges. Male customers would interpret the female employees' friendliness as flirting and make advances on them. Needless to say, the program was dropped.
Another more scientific study took a sample population of 246 student and had them look at photos of a guy and girl studying together. The students were then asked to rate the sexual intent of the woman present in the picture. Men saw the sexual intent as moderate to high, while the women judging the picture saw low to none. My text cites other studies as well and the conclusion of every study was this: Men are hardwired to infer higher sexual or romantic interest then women.
Plus, I have 8 brothers, 4 sisters and have seen this scenario happen again and again, on both gender sides.
Be yourself, be natural, but be prepared. You appear to be quite beautiful so it is likely that most guys are already attracted to you and when you laugh and appear to enjoy your time with them, the natural line of thought follows...;) Good luck!