I’m  18.Can i wear speedos at a public pool/beach abroad?

Yes and No to your question. Yes, if you wanted to wear Speedo at public pool or beach is okay at most place. No, if you do not wanted to wear Speedo at public pool or beach. At last it is your choice to wear or not to wear a speedo in public pool or beach. You can choose to wear different swim wear other than Speedo. TYR swimsuit company is good swimsuit too.

Wear whatever you want to, as long as you are comfortable with what you're wearing at the pool or beach, if anybody says anything, IGNORE THEM!!

I can tell you it's perfectly legal in Australia. They're usually worn by middle-aged men, though.  

Yes, please. I love it.

But then nude is even better.

How else can you be practically naked around hot young women without getting arrested.

Some public (and private/hotel) pools actually require close fitting swimsuits for males (Speedo brief/square cut etc).  This is prevalent in France and may also be that way in other countries.

At beaches it is pretty much anything goes (depending on the beach) and usually does.Go ahead and wear your speedo and enjoy yourself.

[You may want to bring another type of swimsuit along just in case wearing the speedo isn't allowed or not appropriate at that particular pool].

You can, but please don't.

Of course you can.

What do you mean "abroad"?  Where you're actually going makes a significant difference.

if you want. no one is stopping you