  We have analyzed the optical light curves of the blazar OJ 287 obtained with
the Transiting Exoplanet Survey Satellite (TESS) over about 80 days from 2021
October 13 to December 31, with an unprecedented sampling of 2 minutes.
Although significant variability has been found during the entire period, we
have detected two exceptional flares with flux nearly doubling and then nearly
tripling over 2 days in the middle of 2021 November. We went through the light
curves analysis using the excess variance, generalized Lomb-Scargle
periodogram, and Continuous Auto-Regressive Moving Average (CARMA) methods, and
estimated the flux halving/doubling timescales. The most probable shortest
variability timescale was found to be 0.38 days in the rising phase of the
first flare. We briefly discuss some emission models for the variability in
radio-loud active galactic nuclei that could be capable of producing such fast
flares.
