alight upon arrive at arrive upon blunder upon bump into chance upon come across come among come at come down on come on come up against come upon confront descend upon discover serendipitously drop on encounter fall across fall among fall foul of fall in with fall on fall upon get at happen upon hit upon meet meet head-on meet up with meet with pitch upon reach run across run into run smack into run up against run upon settle on strike upon stumble on stumble upon tumble on