I would rephrase that: "weird" is not the best fitting word. "Uncommon" might be.
And I suspect the whole "fetish" concept should be reconsidered.
Why?
A fetish is what psychology calls an uncommon sexual catalyst: something - be it an object, an outfit, a role, or a whole scene - that is arousing to the subject.
Anything that isn't classified as traditional genitalia or "vanilla" sex usually qualifies as a fetish.
Occurence and acceptability are the key here - and they vary a lot depending on the involved parties.
For example, sadomasochism/bondage is more widely accepted as a fetish than tickling.
It requires ropes and tools, it has a dress code, and involves uncommon practices and pain - so in theory, it should be less common. Even shunned because of the submission thing.
It is not: people proudly bear SMBD symbols and come out about it more freely. Tickle fetishists are shy, instead.
As it's been already said, tickling is usually seen as childish or mischievous, so its sexual appeal is not immediately apparent.
It doesn't require - nor has, yet - a complex conduct code that formalizes it into a full blown underground culture: tickling requires a ticklish person and a willing tickler. No latex involved. Just laughter. 😉
Also, tickling often overlaps with more widely known and established fetishes: foot fetish comes to mind.
Finally, light tickling can be incorporated into sexual intercourse without even giving away its nature: if the partner liked it, he/she might not even realize tickling is a fetish at all. It just felt good.
Try being discreet about a "golden shower" fetish. 🙂
Since tickling isn't as flashy and widely known as SMBD, many fail to see it as something originally alternative, and just consider it mundanely weird. 😉
On the whole tickling might be considered a "demi-fetish" - but I realize it is just another big word that will only scare people away.
My humble opinion is we care too much, and tickle too little.
Just keep in mind: everybody needs a sexual catalyst, and ours is not something to be laughed at lightly. 😉 😉 😉
Reg's.