Instead of 'came.' So it's used in the same way as the present tense verb. For instance, "he come down to my place at 9pm" instead of "he <i>came</i> down at 9pm. Seems to be common in Australia among older speakers and those in the country. I think it's from the English. It sounds pretty strange to my ears. Is it used in other parts of the English speaking world?
Using "come" as present-tence
You mean as a past tense? No, I'm not familiar with that here in the US.
It's common to use: ''I win, you win'' for '' I (have) just won, you (have) just won...''
This seems rather unusual. I cannot recall ever hearing this anywhere in the United States or Canada.
This is a corruption of "He ['d/had] come down to my place...", where the 'd/had has been so reduced that it is no longer heard and has gradiating into this new "form".
This is fairly common in Britain. On this page is an example from Tyneside but it cites others from all over the UK
http://www.bl.uk/learning/langlit/sounds/case-studies/geordie/grammar/
http://www.bl.uk/learning/langlit/sounds/case-studies/geordie/grammar/