Trademarks are not a regular part of my practice, but I don’t think there’s a patent practitioner out there who isn’t at least a bit sensitive to trademark issues. US-based sports leagues are famous (or notorious, depending on your perspective) for enforcing the marks in their teams’ logos. The NFL will even go after companies that use the word “Superbowl” in their advertisements if they don’t pay the NFL for that privilege.
With many American-born Israelis and many American tourists passing through Israel, as well as the effort of some sports leagues to branch out beyond the USA, it’s not surprising that (a) there would be people in Israel interested in clothing bearing the logos of their favorite teams, and (b) such clothing might include kippot, viz. the round skullcaps worn by religiously observant Jewish men (and in certain small circles, by women). As one might imagine, the demand for such headgear pales in comparison to, say, the worldwide demand for jerseys of popular NBA players, presumably making it cost-inefficient to obtain a license from the relevant league to produce and sell such skullcaps. (But maybe not, this site advertises an MLB-licensed Chicago Cubs kippa.) Moreover, the places where such demand exists are concentrated geographically in a few US metropolitan areas and in certain parts of Israel. Hence there are a few stores in Jerusalem where one can obtain kippot bearing the logos of various teams. Periodically, there are reports of raids on these stores (probably instigated at the behest of the local attorney representing the league in question), in which unlicensed products are seized. Then after a time, things revert to status quo ante.
A boy I know in Israel, who does not live near an ice rink and has ice skated only a handful of times, if that, became a fan of the Washington Capitals a few years ago. He recently procured a Capitals kippa at one of those Jerusalem stores. Seeing this, my curiosity got the better of me: I checked to see who does the NHL’s TM work in Israel. Apparently no one: there are no NHL-affiliated marks registered in Israel. Which means that the sale or offer for sale of the kippa didn’t constitute infringement of a registered trademark. The NHL could try to bring a passing-off action, but I assume the same small market that mitigated against the (not very large cost of) TM registration in Israel in the first place would mitigate against initiating a(n even more costly) passing-off action against the kippa shop for infringement of an unregistered TM.
So rest easy, kid, you won’t be receiving a cease-and-desist letter about that kippa any time soon.