Usain Bolt's Welcome to Carnival Gift ... Take Our Women, Please!

Usain Bolt got a sweet welcome to Carnival in Trinidad & Tobago -- a human sacrifice ... on the dance floor!

The world's fastest man jumped onstage at a concert called TRIBE Ignite, and yelled ... "I love this country so much!" Trini obviously loves him back because the MC quickly offered him "something special" ... with much junk in her trunk.

It was immediately clear this ain't Usain's first rodeo!

No sign of his longtime gf during this awesome display, but we hear she is on the island too.