1) Appear uninvited 2) Arrive without an invite 3) Call briefly 4) Call on unannounced 5) Cartridge type 6) Drop by 7) Drop by for a sec 8) Drop by on a whim 9) Drop by unannounced 10) Drop by unexpectedly 11) Enter informally 12) Make a brief call 13) Make a quick visit 14) Make a surprise visit 15) Make an appearance 
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