Fitbit reported earnings and revenue that beat expectations, and TheStreet's Jim Cramer says Fitbit's  (FIT - Get Report) CEO James Park has finally gotten in sync with Wall Street in terms of guiding earnings estimates. Cramer says business is good at Fitbit and that Apple (AAPL - Get Report)  is not a true competitor. Cramer wrote on Real Money that Fitbit, GoPro  (GPRO - Get Report) , Etsy (ETSY - Get Report)  and Groupon (GRPN - Get Report) are four 'low expectation' stocks that investors should be in.