I recently started reading Man's Search For Meaning, by Viktor E. Frankl, a psychiatrist and holocaust survivor. In the book, he recounts his experiences of daily life in a concentration camp.
In a passage near the beginning, he explains how he was waiting for a "shower" with several other prisoners, not knowing if it was real or whether it would bring death by gas. Everyone is told to strip to their shoes, belts, or suspenders.
"Where our shoes were concerned, matters were not so simple. Although we were supposed to keep them, those who had fairly decent pairs had to give them up after all and were given in exchange shoes that did not fit. In for real trouble were those prisoners who had followed the apparently well-meant advice (given in the anteroom) of the senior prisoners and had shortened their jackboots by cutting the tops off, then smearing soap on the cut edges to hide the sabotage. The SS men seem to have waited for just that. All suspected of this crime had to go into a small adjoining room. After a time we again heard the lashings of the strap, and the screams of tortured men."
Could someone please explain why a person would want to shorten their jackboots, or why it would be considered sabotage? I'd also like to understand why other prisoners would give such advice if it would potentially lead to someone being punished for it.
Jackboots are calf high military boots. The passage you quote says people with decent boots had them confiscated and replaced with ill fitting substitutes. My interpretation of the passage is that the prisoners were shortening their boots so that they wouldn't be confiscated (short boots would be less useful in a military context as mud, ect can more easily seep in).
The reason it would be considered worthy of punishment is because the prisoners are taking boots that could be used to aid the war effort and rendering it ineffective for that purpose.
As to why the senior prisoners are making the recommendation I see two possible interpretations: 1) the prisoners are trying to be helpful by enabling new prisoners to keep shoes that fit them or 2) the fact that the guards were on the lookout for this means the advice could have been part of a ploy by the guards to identify troublemakers.