Probably someone ate a passion fruit and left the seeds in the garbage. It is very easy to grow in hot weather. (I don't know about your weather... Hot?)

They're everywhere in Texas, makes a beautiful vine with flowers to cover a fence.

In NOrth Carolina we call them May Pops. They grow rampantly in full sun if left to its own devices but can be contained with little effort. Around the end of May each year the vine bears a green fruit (edible in salads) that has the seeds to cultivate if desired.

When we were kids we would arrange them in patterns (an'obstacle course') and at first try not then try to run over them with our bikes. They make a loup POP...thus the name May Pops