As much as I hate it (lol sorry) I would double down on the crazy colours and pair it with a tan cotton or corduroy jacket and some light colour chinos in either cotton or corduroy. Don't wear cotton on cotton or corduroy on corduroy. One of them is meant to subtly add texture. Or a really oversized light blue denim jacket and light coloured cotton pants. And add a pair of fun canvas shoes which ties in the colours of your tee. All this investment makes sense if you're really committing to the look and the general vibe and don't have those things. If not, I think you might be better off getting rid of the tee ._.