Where do you think that pineapple came from?

loool i have NO idea xD

We never find out.

i think troudy (?) brought it , but i have no idea why she would do that ! hopefully , we will find out in S7 or S8 :)

First lets think about when it actually found it's way to his nightstand.

we do know that the pineapple was there when Trudy arrived at his apartment, that's what they told us.

so i'm guessing he got the pineapple between the time barney put him to bed, and the time trudy walked in at his place.

he might have just felt while he was outside "I feel like eating a fresh pineapple" and when off on a short adventure, considering there are no other clues i'd say that he got the pineapple easily.
so he either simply found it or roubou it from somewhere without getting caught. and it must have been close by.

now all there is to figure is where can you get fresh and tasty pineapples in new york city in the morning?

because Ted did say it tasted delicious. we found that out and we solve the case.

and since it's New York I doubt it's that difficult finding fresh pineapples near where ted lives.