blunder upon (?.)
- alight upon
- be all thumbs
- blunder
- blunder away
- blunder into
- blunder on
- boggle
- botch
- bumble
- bump into
- bungle
- butcher
- chance upon
- come across
- come on
- come up against
- come upon
- commit a gaffe
- discover serendipitously
- encounter
- fall in with
- faux pas
- flounder
- fumble
- happen upon
- hit upon
- light upon
- lumber
- mar
- meet up with
- meet with
- miscue
- muddle
- muff
- murder
- play havoc with
- run across
- run into
- run up against
- slip
- spoil
- stumble
- stumble on
- stumble upon
- trip
- tumble on