John Legend & Chrissy Teigen -- HONEYMOON PHASING ... All Over Italian Riviera

John Legend and Chrissy Teigen didn't waste any time getting into the honeymoon phase -- in fact, they've been making out like teenagers all over Italy ever since they tied the knot.

J & C swapped "I Dos" in Lake Como, Italy on Saturday ... and ever since the wedding, they've been sucking face all over the country ... on the beach ... on the street ... in cafes ... even backseats.

The two are currently honeymooning in the seaside town of Portofino ... where it's not uncommon to see topless sunbathers hangin' out on the beach.

Shouldn't be a problem for Chrissy ... or John. As they proved last week, they're very comfortable with nipple exposure.